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Spermatocytogenesis
From Wikipedia, the free encyclopedia
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).
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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 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 undergo mitosis to produce diploid intermediate cells called primary spermatocytes.
Scrotum : layers (skin, Dartos, External spermatic fascia, Cremaster, Internal spermatic fascia) - Perineal raphe - Spermatic cord
Testes: layers (Tunica vaginalis, Tunica albuginea), Appendix, Mediastinum, Lobules, Septa, Leydig cell, Sertoli cell, Blood-testis barrier
Spermatogenesis: Spermatogonium, Spermatocytogenesis, Spermatocyte, Spermatidogenesis, Spermatid, Spermiogenesis, Spermatozoon
seminal tract: Seminiferous tubules (Tubuli seminiferi recti, Rete testis, Efferent ducts) - Epididymis (Appendix) - Vas deferens - Ejaculatory duct Seminal colliculus
urinary tract: Internal urethral orifice - Urethra (Prostatic, Intermediate, Spongy) - Urethral crest - Urethral gland - External urethral orifice
Penis: Corpus cavernosum - Corpus spongiosum - Navicular fossa of male urethra - Glans penis - Fundiform ligament - Suspensory ligament - Foreskin - Frenulum
accessory glands: Seminal vesicles (Excretory duct of seminal gland) - Prostate (Prostatic utricle, Prostatic sinus) - Bulbourethral glands