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The prostate is both an accessory gland of the
male reproductive system The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body and within the pelvis. The main male sex organs are the penis and the test ...
and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the
bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
, with the
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
passing through it. It is described in
gross anatomy Gross anatomy is the study of anatomy at the visible or macroscopic level. The counterpart to gross anatomy is the field of histology, which studies microscopic anatomy. Gross anatomy of the human body or other animals seeks to understand the rela ...
as consisting of lobes and in microanatomy by zone. It is surrounded by an elastic, fibromuscular capsule and contains glandular tissue as well as
connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tissue i ...
. The prostate glands produce and contain fluid that forms part of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...
, the substance emitted during
ejaculation Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component ...
as part of the male sexual response. This prostatic fluid is slightly alkaline, milky or white in appearance. The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of
sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, ...
. The prostatic fluid is expelled in the first part of ejaculate, together with most of the sperm, because of the action of smooth muscle tissue within the prostate. In comparison with the few spermatozoa expelled together with mainly seminal vesicular fluid, those in prostatic fluid have better
motility Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms ...
, longer survival, and better protection of genetic material. Disorders of the prostate include enlargement,
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
, infection, and
cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Poss ...
. The word prostate comes from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic ...
προστάτης, ''prostátēs'', meaning "one who stands before", "protector", "guardian", with the term originally used to describe the seminal vesicles.


Structure

The prostate is a
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
of the
male reproductive system The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body and within the pelvis. The main male sex organs are the penis and the test ...
. In adults, it is about the size of a
walnut A walnut is the edible seed of a drupe of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, ''Juglans regia''. Although culinarily considered a "nut" and used as such, it is not a true bo ...
, and has an average weight of about 11 grams, usually ranging between 7 and 16 grams. The prostate is located in the pelvis. It sits below the
urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
and surrounds the
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
. The part of the urethra passing through it is called the
prostatic urethra The prostatic urethra, the widest and most dilatable part of the urethra canal, is about 3 cm long. It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form o ...
, which joins with the two
ejaculatory duct The ejaculatory ducts (''ductus ejaculatorii'') are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the uret ...
s. The prostate is covered in a surface called the ''prostatic capsule'' or ''prostatic fascia''. The internal structure of the prostate has been described using both lobes and zones. Because of the variation in descriptions and definitions of lobes, the zone classification is used more predominantly. The prostate has been described as consisting of three or four zones. Zones are more typically able to be seen on
histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vi ...
, or in
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to re ...
, such as ultrasound or MRI. The zones are: The "lobe" classification describes lobes that, while originally defined in the fetus, are also visible in gross anatomy, including dissection and when viewed endoscopically. The five lobes are the anterior lobe or isthmus, the posterior lobe, the right and left lateral lobes, and the middle or median lobe. File:Illu prostate lobes.jpg, Lobes of prostate File:Prostate zones.png, Zones of prostate Inside of the prostate, adjacent and parallel to the prostatic urethra, there are two longitudinal muscle systems. On the front side ( ventrally) runs the ''urethral
dilator Dilator or dilatator is a medical term with a number of uses, including: *A surgical instrument or medical implement used to induce dilation, that is, to expand an opening or passage such as the cervix (see cervical dilator), urethra, esophagu ...
'' (''musculus dilatator urethrae''), on the backside (
dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
) runs the muscle switching the urethra into the ejaculatory state (''musculus ejaculatorius'').Michael Schünke, Erik Schulte, Udo Schumacher: ''PROMETHEUS Innere Organe. LernAtlas Anatomie'', vol 2: ''Innere Organe'', Thieme Verlag, Stuttgart/Germany 2012, , p. 298
PDF


Blood and lymphatic vessels

The prostate receives blood through the
inferior vesical artery The inferior vesical artery (or inferior vesicle artery) is an artery of the pelvis which arises from the internal iliac artery and supplies parts of the urinary bladder as well as other structures of the urinary system and structures of the male ...
, internal pudendal artery, and middle rectal arteries. These vessels enter the prostate on its outer surface where it meets the bladder, and travel forward to the apex of the prostate. Both the inferior vesical and the middle rectal arteries often arise together directly from the
internal iliac arteries The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compa ...
. On entering the bladder, the inferior vesical artery splits into a urethral branch, supplying the urethral prostate; and a capsular branch, which travels around the capsule and has smaller branches which perforate into the prostate. The veins of the prostate form a network – the prostatic venous plexus, primarily around its front and outer surface. This network also receives blood from the deep dorsal vein of the penis, and is connected via branches to the vesical plexus and internal pudendal veins. Veins drain into the vesical and then internal iliac veins. The lymphatic drainage of the prostate depends on the positioning of the area. Vessels surrounding the
vas deferens The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube w ...
, some of the vessels in the seminal vesicle, and a vessel from the posterior surface of the prostate drain into the external iliac lymph nodes. Some of the seminal vesicle vessels, prostatic vessels, and vessels from the anterior prostate drain into internal iliac lymph nodes. Vessels of the prostate itself also drain into the obturator and sacral lymph nodes. File:Internal_iliac_branches.PNG , Imaging showing the inferior vesical, inferior pudendal and middle rectal arteries arising from the
internal iliac arteries The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compa ...
. File:Gray611.png , Image showing the external iliac lymph nodes and their positions around the external iliac artery and
vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...


Microanatomy

The prostate consists of glandular and
connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tissue i ...
. Tall column-shaped cells form the lining (the
epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellu ...
) of the glands. These form one layer or may be pseudostratified. The epithelium is highly variable and areas of low
cuboidal Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
or flat cells can also be present, with transitional epithelium in the outer regions of the longer ducts. The glands are formed as many follicles, which in drain into canals and subsequently 12–20 main ducts, These in turn drain into the urethra as it passes through the prostate. There are also a small amount of flat cells, which sit next to the basement membranes of glands, and act as stem cells. The connective tissue of the prostate is made up of fibrous tissue and smooth muscle. The fibrous tissue separates the gland into lobules. It also sits between the glands and is composed of randomly orientated smooth-muscle bundles that are continuous with the bladder. Over time, thickened secretions called
corpora amylacea Corpora amylacea (CA) (from the Latin meaning "starch-like bodies") is a general term for small hyaline masses found in the prostate gland, nervous system, lung, and sometimes in other organs of the body. Corpora amylacea increase in number an ...
accumulate in the gland. File:Prostatehistology.jpg, Microscopic glands of the prostate


Gene and protein expression

About 20,000 protein coding genes are expressed in human cells and almost 75% of these genes are expressed in the normal prostate. About 150 of these genes are more specifically expressed in the prostate, with about 20 genes being highly prostate specific. The corresponding specific proteins are expressed in the glandular and secretory cells of the prostatic gland and have functions that are important for the characteristics of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...
, including prostate-specific
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabo ...
s, such as the prostate specific antigen (PSA), and the Prostatic acid phosphatase.


Development

In the developing
embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
, at the hind end lies an inpouching called the
cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...
. This, over the fourth to the seventh week, divides into a
urogenital sinus The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh we ...
and the beginnings of the
anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segmen ...
, with a wall forming between these two inpouchings called the urorectal septum. The urogenital sinus divides into three parts, with the middle part forming the urethra; the upper part is largest and becomes the
urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
, and the lower part then changes depending on the biological sex of the embryo. The prostatic part of the urethra develops from the middle, pelvic, part of the urogenital sinus, which is of
endoderm Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...
al origin. Around the end of the third month of embryonic life, outgrowths arise from the prostatic part of the urethra and grow into the surrounding
mesenchyme Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every ...
. The cells lining this part of the urethra differentiate into the glandular epithelium of the prostate. The associated mesenchyme differentiates into the dense connective tissue and the smooth muscle of the prostate. Condensation of
mesenchyme Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every ...
,
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
, and Wolffian ducts gives rise to the adult prostate gland, a composite organ made up of several tightly fused glandular and non-glandular components. To function properly, the prostate needs male
hormones A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required fo ...
(
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This incl ...
s), which are responsible for male
sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones (ova, o ...
characteristics. The main male hormone is
testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristic ...
, which is produced mainly by the
testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testos ...
s. It is
dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues includ ...
(DHT), a metabolite of testosterone, that predominantly regulates the prostate. The prostate gland enlarges over time, until the fourth decade of life.


Function

The prostate secretes fluid which becomes part of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...
. Semen is the fluid emitted ( ejaculated) by males during the sexual response. When sperm is emitted, it is transmitted from the
vas deferens The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube w ...
into the male
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
via the
ejaculatory duct The ejaculatory ducts (''ductus ejaculatorii'') are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the uret ...
s, which lie within the prostate gland.
Ejaculation Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component ...
is the expulsion of semen from the urethra. Semen is moved into the urethra following contractions of the smooth muscle of the vas deferens and seminal vesicles, following stimulation, primarily of the
glans penis In male human anatomy, the glans penis, commonly referred to as the glans, is the bulbous structure at the distal end of the human penis that is the human male's most sensitive erogenous zone and their primary anatomical source of sexual pl ...
. Stimulation sends nerve signals via the internal pudendal nerves to the upper lumbar spine; the nerve signals causing contraction act via the
hypogastric nerve The hypogastric nerve is the nerve that transitions between the superior hypogastric plexus and the inferior hypogastric plexus. The hypogastric nerve enters the sympathetic chain at T12- L3. Structure The hypogastric nerve begins where the su ...
s. After traveling into the urethra, the seminal fluid is ejaculated by contraction of the bulbocavernosus muscle. The secretions of the prostate include proteolytic enzymes, prostatic acid phosphatase, fibrinolysin,
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic ...
, and
prostate-specific antigen Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted b ...
. Together with the secretions from the seminal vesicles, these form the major fluid part of semen. It is possible for some men to achieve
orgasm Orgasm (from Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic, involuntary muscular contractions in the pelvic region chara ...
solely through stimulation of the prostate gland, such as via prostate massage or anal intercourse. This has led to the area of the rectal wall adjacent to the prostate to be popularly (yet inaccurately) referred to as the "male
G-spot The G-spot, also called the Gräfenberg spot (for German gynecologist Ernst Gräfenberg), is characterized as an erogenous area of the vagina that, when stimulated, may lead to strong sexual arousal, powerful orgasms and potential female eja ...
". The prostate's changes of shape, which facilitate the mechanical switch between urination and ejaculation, are mainly driven by the two longitudinal muscle systems running along the prostatic urethra. These are the ''urethral
dilator Dilator or dilatator is a medical term with a number of uses, including: *A surgical instrument or medical implement used to induce dilation, that is, to expand an opening or passage such as the cervix (see cervical dilator), urethra, esophagu ...
'' (''musculus dilatator urethrae'') on the urethra's front side, which contracts during urination and thereby shortens and tilts the prostate in its vertical dimension thus widening the prostatic section of the urethral tube, and the muscle switching the urethra into the ejaculatory state (''musculus ejaculatorius'') on its backside. In case of an operation, e.g. because of benign prostatic hyperplasia (BPH), damaging or sparing of these two muscle systems varies considerably depending on the choice of operation type and details of the procedure of the chosen technique. The effects on postoperational urination and ejaculation vary correspondingly. (See also: Surgery for benign prostatic hyperplasia).


Clinical significance


Inflammation

Prostatitis is
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
of the prostate gland. It can be caused by infection with bacteria, or other noninfective causes. Inflammation of the prostate can cause painful urination or ejaculation, groin pain, difficulty passing urine, or constitutional symptoms such as
fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using va ...
or tiredness. When inflamed, the prostate becomes enlarged and is tender when touched during digital rectal examination. The bacteria responsible for the infection may be detected by a urine culture. Acute prostatitis and chronic bacterial prostatitis are treated with
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
s. Chronic non-bacterial prostatitis, or male chronic pelvic pain syndrome is treated by a large variety of modalities including the medications
alpha blockers Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which ...
, nonsteroidal antiinflammatories and
amitriptyline Amitriptyline, sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat cyclic vomiting syndrome (CVS), major depressive disorder and a variety of pain syndromes from neuropathic pain to fibromyalg ...
,
antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides ...
s, and other
anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxi ...
s. Other treatments that are not medications may include
physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patient ...
,
psychotherapy Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of psychological methods, particularly when based on regular personal interaction, to help a person change behavior, increase happiness, and overcome prob ...
, nerve modulators, and
surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...
. More recently, a combination of trigger point and psychological therapy has proved effective for category III prostatitis as well.


Enlarged prostate

An enlarged prostate is called prostatomegaly, with
benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
(BPH) being the most common cause. BPH refers to an enlargement of the prostate due to an increase in the number of cells that make up the prostate () from a cause that is not a malignancy. It is very common in older men. It is often diagnosed when the prostate has enlarged to the point where urination becomes difficult. Symptoms include needing to urinate often ( urinary frequency) or taking a while to get started ( urinary hesitancy). If the prostate grows too large, it may constrict the urethra and impede the flow of urine, making urination painful and difficult, or in extreme cases completely impossible, causing urinary retention. Over time, chronic retention may cause the bladder to become larger and cause a backflow of urine into the kidneys (
hydronephrosis Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of ...
). BPH can be treated with medication, a
minimally invasive procedure Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definitio ...
or, in extreme cases, surgery that removes the prostate. In general, treatment often begins with an alpha-1 adrenergic receptor antagonist medication such as
tamsulosin Tamsulosin, sold under the brand name Flomax among others, is a medication used to treat symptomatic benign prostatic hyperplasia (BPH) and chronic prostatitis and to help with the passage of kidney stones. The evidence for benefit with a k ...
, which reduces the tone of the smooth muscle found in the
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
that passes through the prostate, making it easier for urine to pass through. For people with persistent symptoms, procedures may be considered. The surgery most often used in such cases is
transurethral resection of the prostate Transurethral resection of the prostate (commonly known as a TURP, plural TURPs, and rarely as a transurethral prostatic resection, TUPR) is a urological operation. It is used to treat benign prostatic hyperplasia (BPH). As the name indicates, ...
, in which an instrument is inserted through the urethra to remove prostate tissue that is pressing against the upper part of the urethra and restricting the flow of
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...
. Minimally invasive procedures include transurethral needle ablation of the prostate and transurethral microwave thermotherapy. These outpatient procedures may be followed by the insertion of a temporary
stent In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. A wide variety of stents are used for different purposes, from expanda ...
, to allow normal voluntary urination, without exacerbating irritative symptoms.


Cancer

Prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...
is one of the most common
cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Poss ...
s affecting older men in the UK, US, Northern Europe and Australia, and a significant
cause of death In law, medicine, and statistics, cause of death is an official determination of conditions resulting in a human's death, which may be recorded on a death certificate. A cause of death is determined by a medical examiner. The cause of death is ...
for elderly men worldwide. Often, a person does not have symptoms; when they do occur, symptoms may include urinary frequency, urgency, hesitation and other symptoms associated with BPH. Uncommonly, such cancers may cause weight loss, retention of urine, or symptoms such as back pain due to lesions that have spread outside of the prostate. A digital rectal examination and the measurement of a
prostate-specific antigen Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted b ...
(PSA) level are usually the first investigations done to check for prostate cancer. PSA values are difficult to interpret, because a high value might be present in a person without cancer, and a low value can be present in someone with cancer. The next form of testing is often the taking of a
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dis ...
to assess for tumour activity and invasiveness. Because of the significant risk of
overdiagnosis Overdiagnosis is the diagnosis of disease that will never cause symptoms or death during a patient's ordinarily expected lifetime and thus presents no practical threat regardless of being pathologic. Overdiagnosis is a side effect of screening fo ...
with widespread screening in the general population, prostate cancer screening is controversial. If a tumour is confirmed,
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to re ...
such as an MRI or
bone scan A bone scan or bone scintigraphy is a nuclear medicine imaging technique of the bone. It can help diagnose a number of bone conditions, including cancer of the bone or metastasis, location of bone inflammation and fractures (that may not be vis ...
may be done to check for the presence of tumour in other parts of the body. Prostate cancer that is only present in the prostate is often treated with either surgical removal of the prostate or with
radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radia ...
or by the insertion of small radioactive particles of iodine-125 or palladium-103, called
brachytherapy Brachytherapy is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. ''Brachy'' is Greek for short. Brachytherapy is commonly used as an effective treatment for cervical, prost ...
. Cancer that has spread to other parts of the body is usually treated also with hormone therapy, to deprive a tumour of sex hormones (androgens) that stimulate proliferation. This is often done through the use of GnRH analogues or agents that block the receptors that androgens act at, such as bicalutamide; occasionally, surgical removal of the testes may be done instead. Cancer that does not respond to hormonal treatment, or that progresses after treatment, might be treated with
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothera ...
such as
docetaxel Docetaxel (DTX or DXL), sold under the brand name Taxotere among others, is a chemotherapy medication used to treat a number of types of cancer. This includes breast cancer, head and neck cancer, stomach cancer, prostate cancer and non-small-cell ...
.
Radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radia ...
may also be used to help with pain associated with bony lesions. Sometimes, the decision may be made not to treat prostate cancer. If a cancer is small and localised, the decision may be made to monitor for cancer activity at intervals ("active surveillance") and defer treatment. If a person, because of frailty or other medical conditions or reasons, has a
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...
less than ten years, then the impacts of treatment may outweigh any perceived benefits.


Surgery

Surgery to remove the prostate is called prostatectomy, and is usually done as a treatment for cancer limited to the prostate, or prostatic enlargement. When it is done, it may be done as
open surgery Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definitio ...
or as laparoscopic (keyhole) surgery. These are done under
general anaesthetic General anaesthetics (or anesthetics, see spelling differences) are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma ...
. Usually the procedure for cancer is a radical prostatectomy, which means that the seminal vesicles are removed and vas deferens is also tied off. Part of the prostate can also be removed from within the urethra, called
transurethral resection of the prostate Transurethral resection of the prostate (commonly known as a TURP, plural TURPs, and rarely as a transurethral prostatic resection, TUPR) is a urological operation. It is used to treat benign prostatic hyperplasia (BPH). As the name indicates, ...
(TURP). Open surgery may involve a cut that is made in the
perineum The perineum in humans is the space between the anus and scrotum in the male, or between the anus and the vulva in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), includi ...
, or via an approach that involves a cut down the midline from the belly button to the pubic bone. Open surgery may be preferred if there is a suspicion that lymph nodes are involved and they need to be removed or biopsied during a procedure. A perineal approach will not involve lymph node removal and may result in less pain and a faster recovery following an operation. A TURP procedure uses a tube inserted into the urethra via the penis and some form of heat, electricity or laser to remove prostate tissue. The whole prostate can be removed. Complications that might develop because of surgery include
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in ger ...
and
erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of mal ...
because of damage to nerves during the operation, particularly if a cancer is very close to nerves.
Ejaculation Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component ...
of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...
will not occur during
orgasm Orgasm (from Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic, involuntary muscular contractions in the pelvic region chara ...
if the vas deferens are tied off and seminal vesicles removed, such as during a radial prosatectomy. This will mean a man becomes infertile. Sometimes, orgasm may not be able to occur or may be painful. The penis length may change if the part of the urethra within the prostate is also removed. General complications due to surgery can also develop, such as
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
s,
bleeding Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
, inadvertent damage to nearby organs or within the abdomen, and the formation of
blood clot A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of c ...
s.


History

The prostate was first formally identified by Venetian anatomist Niccolò Massa in ''Anatomiae libri introductorius'' (Introduction to Anatomy) 1536 and illustrated by
Flemish Flemish (''Vlaams'') is a Low Franconian dialect cluster of the Dutch language. It is sometimes referred to as Flemish Dutch (), Belgian Dutch ( ), or Southern Dutch (). Flemish is native to Flanders, a historical region in northern Belgium; ...
anatomist Andreas Vesalius in ''Tabulae anatomicae sex'' (six anatomical tables) in 1538. Massa described it as a "glandular flesh upon which rests the neck of the bladder," and Vesalius as a "glandular body". The first time a word similar to 'prostate' was used to describe the gland is credited to André du Laurens in 1600, who described it as a term already in use by anatomists at the time. The term was however used at least as early as 1549 by French surgeon Ambroise Pare. At the time, Du Laurens was describing what was considered to be a pair of organs (not the single two-lobed organ), and the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of ...
term ''prostatae'' that was used was a mistranslation of the term for the
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic ...
word used to describe the seminal vesicles, ''parastatai''; although it has been argued that surgeons in Ancient Greece and Rome must have at least seen the prostate as an anatomical entity. The term ''prostatae'' was taken rather than the grammatically correct ''prostator'' (singular) and ''prostatores'' (plural) because the
gender Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most cultures us ...
of the Ancient Greek term was taken as female, when it was in fact male. The fact that the prostate was one and not two organs was an idea popularised throughout the early 18th century, as was the English language term used to describe the organ, ''prostate'', attributed to William Cheselden. A
monograph A monograph is a specialist work of writing (in contrast to reference works) or exhibition on a single subject or an aspect of a subject, often by a single author or artist, and usually on a scholarly subject. In library cataloging, ''monograp ...
, "Practical observations on the treatment of the diseases of the prostate gland" by Everard Home in 1811, was important in the history of the prostate by describing and naming anatomical parts of the prostate, including the median lobe. The idea of the five lobes of the prostate was popularized following anatomical studies conducted by American urologist Oswald Lowsley in 1912. John E. McNeal first proposed the idea of "zones" in 1968; McNeal found that the relatively homogeneous cut surface of an adult prostate in no way resembled "lobes" and thus led to the description of "zones". Prostate cancer was first described in a speech to the Medical and Chiurgical Society of London in 1853 by surgeon
John Adams John Adams (October 30, 1735 – July 4, 1826) was an American statesman, attorney, diplomat, writer, and Founding Father who served as the second president of the United States from 1797 to 1801. Before his presidency, he was a leader of ...
and increasingly described by the late 19th century. Prostate cancer was initially considered a rare disease, probably because of shorter life expectancies and poorer detection methods in the 19th century. The first treatments of prostate cancer were surgeries to relieve urinary obstruction. Samuel David Gross has been credited with the first mention of a prostatectomy, as "too absurd to be seriously entertained" The first removal for prostate cancer (radical perineal prostatectomy) was first performed in 1904 by Hugh H. Young at
Johns Hopkins Hospital The Johns Hopkins Hospital (JHH) is the teaching hospital and biomedical research facility of the Johns Hopkins School of Medicine, located in Baltimore, Maryland, U.S. It was founded in 1889 using money from a bequest of over $7 million (1873 mo ...
; partial removal of the gland was conducted by Theodore Billroth in 1867.
Transurethral resection of the prostate Transurethral resection of the prostate (commonly known as a TURP, plural TURPs, and rarely as a transurethral prostatic resection, TUPR) is a urological operation. It is used to treat benign prostatic hyperplasia (BPH). As the name indicates, ...
(TURP) replaced radical prostatectomy for symptomatic relief of obstruction in the middle of the 20th century because it could better preserve penile erectile function. Radical retropubic prostatectomy was developed in 1983 by Patrick Walsh. In 1941, Charles B. Huggins published studies in which he used
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
to oppose testosterone production in men with metastatic prostate cancer. This discovery of "chemical
castration Castration is any action, surgical, chemical, or otherwise, by which an individual loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical castration uses pharmaceu ...
" won Huggins the 1966
Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accordi ...
. The role of the gonadotropin-releasing hormone (GnRH) in reproduction was determined by Andrzej W. Schally and
Roger Guillemin Roger Charles Louis Guillemin (born January 11, 1924) is a French-American neuroscientist. He received the National Medal of Science in 1976, and the Nobel prize for medicine in 1977 for his work on neurohormones, sharing the prize that year w ...
, who both won the 1977 Nobel Prize in Physiology or Medicine for this work. GnRH receptor agonists, such as leuprorelin and goserelin, were subsequently developed and used to treat prostate cancer.
Radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radia ...
for prostate cancer was first developed in the early 20th century and initially consisted of intraprostatic
radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather ...
implants. External beam radiotherapy became more popular as stronger
X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10  picometers to 10 nanometers, corresponding to frequencies in the range 30  ...
radiation sources became available in the middle of the 20th century.
Brachytherapy Brachytherapy is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. ''Brachy'' is Greek for short. Brachytherapy is commonly used as an effective treatment for cervical, prost ...
with implanted seeds (for prostate cancer) was first described in 1983. Systemic
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothera ...
for prostate cancer was first studied in the 1970s. The initial regimen of
cyclophosphamide Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer ...
and 5-fluorouracil was quickly joined by multiple regimens using a host of other systemic chemotherapy drugs.


Other animals

The prostate is found only in mammals. The prostate glands of male
marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a p ...
s are proportionally larger than those of
placental Placental mammals ( infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguish ...
mammals. The presence of a functional prostate in monotremes is controversial, and if monotremes do possess functional prostates, they may not make the same contribution to semen as in other mammals. The structure of the prostate varies, ranging from tubuloalveolar (as in humans) to branched tubular. The gland is particularly well developed in dogs, foxes and boars, though in other mammals, such as bulls, it can be small and inconspicuous.Nelsen, O. E. (1953
''Comparative embryology of the vertebrates''
Blakiston, page 31.
In other animals, such as marsupials and small ruminants, the prostate is disseminate, meaning not specifically localisable as a distinct tissue, but present throughout the relevant part of the urethra; in other animals, such as
red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...
and American elk, it may be present as a specific organ and in a disseminate form. In some marsupial species, the size of the prostate gland changes seasonally. The prostate is the only accessory gland that occurs in male dogs. Dogs can produce in one hour as much prostatic fluid as a human can in a day. They excrete this fluid along with their urine to mark their territory. Additionally, dogs are the only species apart from humans seen to have a significant incidence of prostate cancer. In
cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
(
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and p ...
s,
dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
s,
porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals an ...
s) the prostate is composed of diffuse urethral glands and is surrounded by a very powerful compressor muscle. The prostate gland originates with tissues in the urethral wall. This means the
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
, a compressible tube used for urination, runs through the middle of the prostate. This leads to an evolutionary design fault for some mammals, including human males. The prostate is prone to infection and enlargement later in life, constricting the urethra so urinating becomes slow and painful. Prostatic secretions vary among species. They are generally composed of simple sugars and are often slightly alkaline.


Skene's gland

Because the
Skene's gland In female human anatomy, Skene's glands or the Skene glands ( , also known as the lesser vestibular glands, paraurethral glands) are glands located around the lower end of the urethra. The glands are surrounded by tissue that swells with blood ...
and the male prostate act similarly by secreting
prostate-specific antigen Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted b ...
(PSA), which is an ejaculate protein produced in males, and of prostate-specific
acid phosphatase Acid phosphatase (EC 3.1.3.2, acid phosphomonoesterase', phosphomonoesterase, glycerophosphatase, acid monophosphatase, acid phosphohydrolase, acid phosphomonoester hydrolase, uteroferrin, acid nucleoside diphosphate phosphatase, orthophosphoric-m ...
, the Skene's gland is sometimes referred to as the "female prostate". Although it is homologous to the male prostate (developed from the same
embryological Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...
tissues), various aspects of its development in relation to the male prostate are widely unknown and a matter of research.


References


Citations


General and cited sources

* ; Attribution * Portions of the text of this article originate from NIH Publication No. 02-4806, a public domain resource.


External links

* {{Authority control Exocrine system Glands Mammal male reproductive system Sexual anatomy