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Leydig
Leydig cells, also known as interstitial cells of the testes and interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle and produce testosterone in the presence of luteinizing hormone (LH). They are polyhedral in shape and have a large, prominent nucleus, an eosinophilic cytoplasm, and numerous lipid-filled vesicles. Males have two types of leydig cells that appear in two distinct stages of development: the fetal type and the adult type. 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 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 (SER). Besides the abundance of SER with scattered patches of rough endoplasmic reticulum, several mitochondria are also prominent within the cyto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 thecoma but also containing cells typical of steroid hormone-secreting cells were reported. Some of the tumors were classified as luteinized thecomas because the steroid cells resembled lutein cells and lacked crystalloids of Reinke. Others were classified as stromal Leydig cell tumors as seen in tumors of the testes because Reinke crystalloids were identified in the steroid cells. The stromal Leydig tumors occurred at an average age of 61 years and were associated with ovarian hyperandrogenism which led to virilization in some cases, endometrial hyperplasia in other cases, and endometrial hyperplasia with carcinoma in the rest of the cases. Luteinized thecomas and stromal Leydig cell tumors are indistinguishable except for the presence of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testosterone
Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of androgenic hair, body hair. It is associated with increased aggression, sex drive, Dominance hierarchy, dominance, courtship display, and a wide range of behavioral characteristics. In addition, testosterone in both sexes is involved in health and well-being, where it has a significant effect on overall mood, cognition, social and sexual behavior, metabolism and energy output, the cardiovascular system, and in the prevention of osteoporosis. Insufficient levels of testosterone in men may lead to abnormalities including frailty, accumulation of adipose fat tissue within the body, anxiety and depression, sexual performance issues, and bone loss. Excessiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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) from the hypothalamus. In females, an acute rise of LH known as an LH surge, triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell–stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone. It acts synergistically with follicle-stimulating hormone ( FSH). Etymology The term luteinizing comes from the Latin "luteus", meaning "yellow". This is in reference to the corpus luteum, which is a mass of cells that forms in an ovary after an ovum (egg) has been discharged. The corpus luteum is so named because it often has a distinctive yellow color. The process of forming the corpus luteum is known as " luteinization", and thus the hormone that triggers th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Androgens
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both males and females during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT ''in utero'' causes differentiation of the penis, scrotum and prostate. In adulthood, DHT contributes to balding, prostate growth, and sebaceous gland activity. Although androgens are commonly thought of only as male sex hormones, females also have them, but at lower levels: they function in libido and sexual arousal. Androgens are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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-stimulating hormone (FSH) secreted by the adenohypophysis and express FSH receptor on their membranes. History Sertoli cells are named after Enrico Sertoli, an Italian physiologist who discovered them while studying medicine at the University of Pavia, Italy. He published a description of his eponymous cell in 1865. The cell was discovered by Sertoli with a Belthle microscope which had been purchased in 1862. In the 1865 publication, his first description used the terms "tree-like cell" or "stringy cell"; most importantly, he referred to these as "mother cells". Other scientists later used Enrico's family name to label these cells in publications, beginning in 1888. As of 2006, two textbooks that are devoted specifically to the Sertoli cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatocyte
Spermatocytes are a type of male gametocyte in animals. They derive from immature germ cells called spermatogonia. They are found in the testis, in a structure known as the seminiferous tubules. There are two types of spermatocytes, primary and secondary spermatocytes. Primary and secondary spermatocytes are formed through the process of spermatocytogenesis. Primary spermatocytes are diploid (2N) cells. After meiosis I, two secondary spermatocytes are formed. Secondary spermatocytes are haploid (N) cells that contain half the number of chromosomes. In all animals, Male, males produce spermatocytes, even hermaphrodites such as Caenorhabditis elegans, ''C. elegans'', which exist as a male or hermaphrodite. In hermaphrodite ''C. elegans'', sperm production occurs first and is then stored in the spermatheca. Once the egg cell, eggs are formed, they are able to self-fertilize and produce up to 350 offspring, progeny. Development At puberty, spermatogonia located along the walls of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogonium
A spermatogonium (plural: ''spermatogonia'') is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testicles. There are three subtypes of spermatogonia in humans: Type A (dark) cells, with dark nuclei. These cells are reserve spermatogonial stem cells which do not usually undergo active mitosis. Type A (pale) cells, with pale nuclei. These are the spermatogonial stem cells that undergo active mitosis. These cells divide to produce Type B cells. Type B cells, which undergo growth and become primary spermatocytes. Types of spermatogonia Spermatogonia are often classified into different types depending on their stage in the differentiation process. In humans and most mammals, spermatogonia are divided into two types, A and B, but this can differ for other organisms. There are three subtypes of spermatogonia in humans: *Type A (dark) cells, with dark nuclei. These cells are reserve spermatogonia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testes
A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of androgens, primarily testosterone. The release of testosterone is regulated by luteinizing hormone (LH) from the anterior pituitary gland. Sperm production is controlled by follicle-stimulating hormone (FSH) from the anterior pituitary gland and by testosterone produced within the gonads. Structure Appearance Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's anatomy. For 85% of men, the right testis hangs lower than the left one. Measurement and volume The volume of the testicle can be estimated by palpating it and comparing it to ellipsoids (an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 female, the testicles in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes. On average, females begin puberty at age 10½ and complete puberty at ages 15-17; males begin at ages 11½-12 and complete pube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myofibroblast
A myofibroblast is a cell phenotype that was first described as being in a state between a fibroblast and a smooth muscle cell. Structure Myofibroblasts are contractile web-like fusiform cells that are identifiable by their expression of α-smooth muscle actin within their cytoplasmic stress fibers. In the gastrointestinal and genitourinary tracts, myofibroblasts are found subepithelially in mucosal surfaces. Here they not only act as a regulator of the shape of the crypts and villi, but also act as stem-niche cells in the intestinal crypts and as parts of atypical antigen-presenting cells. They have both support as well as paracrine function in most places. Location Myofibroblasts were first identified in granulation tissue during skin wound healing. Typically, these cells are found in granulation tissue, scar tissue (fibrosis) and the stroma of tumours. They also line the gastrointestinal tract, wherein they regulate the shapes of crypts and villi. Markers Myofibroblas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seminiferous Tubules
Seminiferous tubules are located within the testicles, 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 as Sertoli cells, which are tall, columnar type cells that line the tubule. In between the Sertoli cells are spermatogenic cells, which differentiate through meiosis to sperm cells. Sertoli cells function to nourish the developing sperm cells. They secrete androgen-binding protein, a binding protein which increases the concentration of testosterone. There are two types: convoluted and straight, convoluted toward the lateral side, and straight as the tubule comes medially to form ducts that will exit the testis. The seminiferous tubules are formed from the testis cords that develop from the primitive gonadal cords, formed from the gonadal ridge. Function Spermatogenesis, the process for producing spermatozoa, takes place i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steroid
A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and as signal transduction, signaling molecules. Examples include the lipid cholesterol, sex hormones estradiol and testosterone, anabolic steroids, and the anti-inflammatory corticosteroid drug dexamethasone. Hundreds of steroids are found in Fungus, fungi, plants, and animals. All steroids are manufactured in cells from a sterols, sterol: Cholesterol, cholesterol (animals), lanosterol (opisthokonts), or cycloartenol (plants). All three of these molecules are produced via Cyclic compound, cyclization of the triterpene squalene. Structure The steroid nucleus (parent structure, core structure) is called gonane (cyclopentanoperhydrophenanthrene). It is typically composed of seventeen carbon atoms, bonded in fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
