What is Spermatocytogenesis?

Information about Spermatocytogenesis

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Schematic diagram of Spermatocytogenesis
Spermatocytogenesis is the male form of gametocytogenesis and involves stem cells dividing to replace themselves and to produce a population of cells destined to become mature sperm.

The stem cells involved are called spermatogonia and are a specific type of stem cell known as gametogonia.

Three functionally separate spermatogonial cell types are recognised on the basis of the appearance of the nuclei: type A dark spermatogonia (Ad), type A pale spermatogonia (Ap), and type B spermatogonia (B).

Type Ad spermatogonia ("dark")

The population of spermatogonia is maintained by type Ad spermatogonia.

This type is capable of dividing to produce either two identical type Ad spermatogonia or two type Ap spermatogonia. type Ad spermatogonia do not directly participate in producing sperm and simply ensure a supply of stem cells to participate in spermatogenesis is maintained.

Type Ap spermatogonia ("pale")

Type Ap spermatogonia repeatedly divide mitotically to produce identical cell clones linked by a cytoplasmic bridge to form a plasmodium.

The connections between cells allow development to be synchronised. When repeated division ceases, the cells differentiate into type B spermatagonia. This stage is referred to as the spermatogonial phase.

Type B spermatagonia

Type B spermatagonia undergo mitosis to produce diploid intermediate cells called primary spermatocytes.

See also

External links

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Male reproductive system
Scrotumlayers (skin, Dartos, External spermatic fascia, Cremaster, Internal spermatic fascia) • Perineal raphe • Spermatic cord
Testeslayers (Tunica vaginalis, Tunica albuginea) • Appendix • Mediastinum • Lobules • Septa • Leydig cell • Sertoli cell • Blood-testis barrier
SpermatogenesisSpermatogonium • Spermatocytogenesis • Spermatocyte • Spermatidogenesis • Spermatid • Spermiogenesis • Spermatozoon
seminal tractSeminiferous tubules (Tubuli seminiferi recti, Rete testis, Efferent ducts) • Epididymis  (Appendix) • Vas deferens • Ejaculatory duct  Seminal colliculus
urinary tractInternal urethral orifice • Urethra (Prostatic, Intermediate, Spongy) • Urethral crest • Urethral gland • External urethral orifice
PenisCorpus cavernosum • Corpus spongiosum • Navicular fossa of male urethra • Glans penis • Fundiform ligament • Suspensory ligament • Foreskin • Frenulum
accessory glandsSeminal vesicles  (Excretory duct of seminal gland) • Prostate  (Prostatic utricle, Prostatic sinus) • Bulbourethral glands
Gametocytogenesis is the creation of gametocytes by mitotic division of gametogonia. Males and females of a species that reproduces sexually have different forms of gametocytogenesis:
  • spermatocytogenesis (male)
  • oocytogenesis (female)

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A spermatogonium (plural: spermatogonia) is an intermediary male gametogonium (a kind of germ cell) in the production of spermatozoa.

There are two subtypes:

Type A(d)
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A gametogonium (plural gametogonia) is a germ cell that divides into gametocytes during gametogenesis. Male gametogonia are called spermatogonia, and female gametogonia are called oogonia.
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nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles]]

In cell biology, the nucleus (pl.
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A plasmodium is also the macroscopic form of the protist known as a slime mould.

Plasmodium



Scientific classification

Domain: Eukaryota
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A spermatocyte is a male gametocyte which is derived from a spermatogonium. Initially in spermatogenesis, a spermatogonium divides by mitosis into two so-called primary spermatocytes.
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Oogenesis or rarely oögenesis is the creation of an ovum (egg cell). It is the female process of gametogenesis. It involves the various stages of immature ova.

Oogenesis in mammals

In mammals, oogenesis occurs in the ovarian follicle of the ovary.
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Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. Spermatozoa are the mature male gametes, in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis.
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human male reproductive system is a series of organs located outside of the body and around the pelvic region of a male that contribute towards the reproductive process.

The male contributes to reproduction by producing spermatozoa.
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The reproductive system is the ensembles and interactions of organs and/or substances within an organism that strictly pertain to reproduction. As an example, this would include in the case of female mammals, the hormone estrogen, ova, and the uterus and the vagina, and the breasts.
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In some male mammals, the scrotum is a protuberance of skin and muscle containing the testicles. It is an extension of the abdomen, and is located between the penis and anus.
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The dartos is a layer of smooth muscular fiber outside the external spermatic fascia but below the skin.

Gender differences

  • In males it is termed tunica dartos and lies beneath the skin of the scrotum.

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The external spermatic fascia (intercrural or intercolumnar fascia) is a thin membrane, prolonged downward around the surface of the cord and testis. It is separated from the dartos tunic by loose areolar tissue.
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The cremaster muscle is a muscle that covers the testis.

Contraction

Its function is to raise and lower the scrotum in order to regulate the temperature of the testis and promote spermatogenesis.
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The internal spermatic fascia (infundibuliform fascia) is a thin layer, which loosely invests the cord; it is a continuation downward of the transversalis fascia.

Additional images



The scrotum.

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The perineal raphe extends from the anus, through the mid-line of the scrotum (scrotal raphe) and upwards through the posterior mid-line aspect of the penis (penile raphe).

It is observed as a noticeable line.
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spermatic cord is the name given to the cord-like structure in males formed by the vas deferens and surrounding tissue that run from the abdomen down to each testicle.

Contents of spermatic cord


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The testicle (from Latin testis, meaning "witness",[1] plural testes) or ballock is the male generative gland in animals. This article will concentrate on mammalian testicles unless otherwise noted.
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The tunica vaginalis is the serous covering of the testis.

It is a pouch of serous membrane, derived from the saccus vaginalis of the peritoneum, which in the fetus preceded the descent of the testis from the abdomen into the scrotum.
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For other structures with the same name, see Tunica albuginea.

The Tunica Albuginea is the fibrous covering of the testis.

It is a dense blue-white membrane, composed of bundles of white fibrous tissue which interlace in every direction.
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The appendix testis (or Hydatid of Morgagni) is a vestigial remnant of the Müllerian duct, present on the upper pole of the testis and attached to the tunica vaginalis. It is present about 90% of the time.
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The mediastinum testis is a network of fibrous connective tissue that extends from the upper to near the lower extremity of the testis, and is wider above than below.
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The glandular structure of the testis consists of numerous lobules.

Their number, in a single testis, is estimated by Berres at 250, and by Krause at 400.

They differ in size according to their position, those in the middle of the gland being larger and longer.
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septa which extend between the mediastinum testis and the tunica albuginea, and consists of from one to three, or more, minute convoluted tubes, the tubuli seminiferi.

Additional images




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Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle. They can secrete testosterone and are often closely related to nerves. Leydig cells have round vesicular nuclei and a granular eosinophilic cytoplasm.
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A Sertoli cell (a kind of sustentacular cell) is a 'nurse' cell of the testes which is part of a seminiferous tubule.

It is activated by follicle-stimulating hormone, and has FSH-receptor on its membranes.
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The blood-testis barrier (abbreviated as BTB) is a physical barrier between the blood vessels and the seminiferous tubules of the animal testes.

The barrier is formed by tight connections between the Sertoli cells, which are sustentacular cells (supporting cells) of the
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Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. Spermatozoa are the mature male gametes, in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis.
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A spermatogonium (plural: spermatogonia) is an intermediary male gametogonium (a kind of germ cell) in the production of spermatozoa.

There are two subtypes:

Type A(d)
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