Spermatogonium

Spermatogonium
Germinal epithelium of the testicle. 1 basal lamina, 2 spermatogonia, 3 spermatocyte 1st order, 4 spermatocyte 2nd order, 5 spermatid, 6 mature spermatid, 7 Sertoli cell, 8 tight junction (blood testis barrier)
Histological section through testicular parenchyma of a boar. 1 Lumen of Tubulus seminiferus contortus, 2 spermatids, 3 spermatocytes, 4 spermatogonia, 5 Sertoli cell, 6 Myofibroblasts, 7 Leydig cells, 8 capillaries
Gray's	subject #258 1243
MeSH	Spermatogonia

A spermatogonium (plural: spermatogonia) is an undifferentiated male germ cell, originating in a seminiferous tubule and dividing into two primary spermatocytes (a kind of germ cell) in the production of spermatozoa.

There are three subtypes:

• Type A(d) cells, with dark nuclei. These cells replicate to ensure a constant supply of spermatogonia to fuel spermatogenesis.

• Type A(p) cells, with pale nuclei. These cells divide by mitosis to produce Type B cells.
• Type B cells, which divide to give rise to primary spermatocytes.

Each primary spermatocyte duplicates its DNA and subsequently undergoes meiosis I to produce two haploid secondary spermatocytes. Each of the two secondary spermatocytes further undergo meiosis II to produce two spermatids (haploid). (1 primary spermatocyte => 4 spermatids)

The spermatids then undergo spermiogenesis to produce spermatozoa.

Additional images

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  Transverse section of a tubule of the testis of a rat. X 250.

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  Schematic diagram of Spermatocytogenesis

References