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Leydig cells, also known as interstitial cells of the testes and interstitial cells of Leydig, are found adjacent to the
seminiferous tubules Seminiferous tubules are located within the testes, and are the specific location of meiosis, and the subsequent creation of male gametes, namely spermatozoa. Structure The epithelium of the tubule consists of a type of sustentacular cells known ...
in 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 testostero ...
and produce
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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
in the presence of
luteinizing hormone Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
(LH). They are polyhedral in shape and have a large, prominent
nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...
, an
eosinophilic Eosinophilic (Greek suffix -phil-, meaning ''loves eosin'') is the staining of tissues, cells, or organelles after they have been washed with eosin, a dye. Eosin is an acidic dye for staining cell cytoplasm, collagen, and muscle fibers. ''E ...
cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
, and numerous lipid-filled vesicles.


Structure

The mammalian Leydig cell is a polyhedral epithelioid cell with a single eccentrically located ovoid nucleus. The nucleus contains one to three prominent
nucleoli The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of s ...
and large amounts of dark-staining peripheral heterochromatin. The acidophilic cytoplasm usually contains numerous membrane-bound lipid droplets and large amounts of
smooth endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ...
(SER). Besides the abundance of SER with scattered patches of
rough endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
, several
mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
are also prominent within the
cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
.
Reinke crystals Reinke crystals are rod-like cytoplasmic inclusions which can be found in Leydig cells of the testes. Occurring only in adult humans and wild bush rats, their function is unknown. Ovarian stromal tumors having a predominant pattern of fibroma or t ...
have
lipofuscin Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, reti ...
pigment and rod-shaped crystal-like structures 3 to 20 micrometres in diameter. Adult-type Leydig cells differentiate in the post-natal testis and are dormant until
puberty Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. ...
. They are preceded in the testis by a population of fetal-type Leydig cells from the 8th to the 20th week of
gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
, which produce enough testosterone for masculinisation of a male fetus.


Androgen production

Leydig cells release a class of
hormones A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and beh ...
called
androgens 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 in ...
(19-carbon
steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...
s). They secrete
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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
, androstenedione and
dehydroepiandrosterone Dehydroepiandrosterone (DHEA), also known as androstenolone, is an endogenous steroid hormone precursor. It is one of the most abundant circulating steroids in humans. DHEA is produced in the adrenal glands, the gonads, and the brain. It fun ...
(DHEA), when stimulated by the
luteinizing hormone Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
(LH), which is released from the
anterior pituitary A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis or pars anterior) is the glandular, anterior lobe that together with the posterior lobe (posterior pituitary, or the neurohypophysis) makes up the p ...
in response to
gonadotropin releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and released ...
which in turn is released by the
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
. LH binds to its receptor ( LHCGR) which is a
G-protein coupled receptor G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of protein family, evolution ...
and consequently increases the production of
cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...
. cAMP, in turn through
protein kinase A In cell biology, protein kinase A (PKA) is a family of enzymes whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (). PKA has several functions in the cell, including regulatio ...
activation, stimulates cholesterol translocation from intracellular sources (primarily the plasma membrane and intracellular stores) to the mitochondria, firstly to the
outer mitochondrial membrane A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...
and then cholesterol needs to be translocated to the
inner mitochondrial membrane The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space. Structure The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. ...
by steroidogenic acute regulatory protein, which is the rate-limiting step in steroid biosynthesis. This is followed by
pregnenolone Pregnenolone (P5), or pregn-5-en-3β-ol-20-one, is an endogenous steroid and precursor/ metabolic intermediate in the biosynthesis of most of the steroid hormones, including the progestogens, androgens, estrogens, glucocorticoids, and mineraloc ...
formation from the translocated cholesterol via the
cholesterol side-chain cleavage enzyme Cholesterol side-chain cleavage enzyme is commonly referred to as P450scc, where "scc" is an acronym for side-chain cleavage. P450scc is a mitochondrial enzyme that catalyzes conversion of cholesterol to pregnenolone. This is the first reactio ...
, which is found in the inner mitochondrial membrane, eventually leading to testosterone synthesis and secretion by Leydig cells. In rats,
prolactin Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...
(PRL) increases the response of Leydig cells to LH by increasing the number of LH receptors expressed on Leydig cells.


Clinical significance

Leydig cells may grow uncontrollably and form a
Leydig cell tumour Leydig cell tumour, also Leydig cell tumor (US spelling), (testicular) interstitial cell tumour and (testicular) interstitial cell tumor (US spelling), is a member of the sex cord-stromal tumour group of ovarian and testicular cancers. It arises f ...
. These may be hormonally active, i.e. secrete testosterone. The function of
Reinke crystals Reinke crystals are rod-like cytoplasmic inclusions which can be found in Leydig cells of the testes. Occurring only in adult humans and wild bush rats, their function is unknown. Ovarian stromal tumors having a predominant pattern of fibroma or t ...
is unknown, but they appear in the case of Leydig cell tumours. They are found in less than half of all Leydig cell tumors, but they serve to clinch the diagnosis of a Leydig cell tumor. No other interstitial cell within the testes has a nucleus or cytoplasm with these characteristics, making identification relatively easy. While any age is susceptible to a Leydig cell tumour, Leydig cell tumours are more common in people aged 5 to 10 and 30 to 35. A Leydig cell tumour in a child usually causes
precocious puberty In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of childr ...
. About 10% of boys with the tumour have
gynecomastia Gynecomastia (also spelled gynaecomastia) is the abnormal non-cancerous enlargement of one or both breasts in males due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Updated by Brent Wisse ( ...
. Although a Leydig cell tumour is always
benign Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
in children, it is
malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
in 10% to 15% of adults. It is the most common
testicular cancer Testicular cancer is cancer that develops in the testicles, a part of the male reproductive system. Symptoms may include a lump in the testicle, or swelling or pain in the scrotum. Treatment may result in infertility. Risk factors include an ...
of non-
germ cell Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during emb ...
origin.
Sonography Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, musc ...
may be used to identify
cystic A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble); ...
areas, but it is unable to tell benign tumours apart from malignant tumours.
Adrenomyeloneuropathy Adrenoleukodystrophy (ALD) is a genetic disorder, disease linked to the X chromosome. It is a result of fatty acid buildup caused by peroxisome#Metabolic functions, peroxisomal fatty acid beta oxidation which results in the accumulation of very lo ...
is another example of a disease affecting the Leydig cell. In this case, a person's testosterone may fall despite higher-than-normal levels of LH and
follicle-stimulating hormone Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, an ...
(FSH).


Etymology

Leydig cells are named after the German anatomist
Franz Leydig Franz von Leydig, also Franz Leydig (; 21 May 1821 – 13 April 1908), was a German zoologist and comparative anatomist."Franz von Leydig" (biography), Ole Daniel Enerson, 2006, WhoNamedIt.coWNI-675-Leydig Life Franz Leydig was born on 21 May ...
, who discovered them in 1850.


Additional images

File:Gray1114.png, Section of a genital cord of the testis of a human embryo 3.5 cm long File:Leydig cell tumour2.jpg, Intermediate magnification
micrograph A micrograph or photomicrograph is a photograph or digital image taken through a microscope or similar device to show a magnified image of an object. This is opposed to a macrograph or photomacrograph, an image which is also taken on a mic ...
of a Leydig cell tumour,
H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnos ...
File:Leydig cell tumour3.jpg, High magnification
micrograph A micrograph or photomicrograph is a photograph or digital image taken through a microscope or similar device to show a magnified image of an object. This is opposed to a macrograph or photomacrograph, an image which is also taken on a mic ...
of a Leydig cell tumour,
H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnos ...
File:Leydig cells.JPG, Cross-section of seminiferous tubules; arrows indicate location of Leydig cells


See also

*
Sertoli cell Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-stimul ...
* Sertoli-Leydig cell tumour *
List of human cell types derived from the germ layers This is a list of cells in humans derived from the three embryonic germ layers – ectoderm, mesoderm, and endoderm. Cells derived from ectoderm Surface ectoderm Skin * Trichocyte * Keratinocyte Anterior pituitary * Gonadotrope * Corticotro ...


References


External links

*
Reproductive PhysiologyDiagram at umassmed.edu
{{DEFAULTSORT:Leydig Cell Steroid hormone secreting cells Animal reproductive system Human cells Scrotum