Spermatocytogenesis is the male form of gametocytogenesis

Gametocytogenesis

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 * oocytogenesis...

 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

Cell nucleus

In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...

: 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

Mitosis

Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...

 to produce identical cell clones linked by cytoplasmic bridges.

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 spermatogonia

Type B spermatogonia undergo mitosis to produce diploid intermediate cells called primary spermatocyte

Spermatocyte

A spermatocyte is a male gametocyte, derived from a spermatogonium, which is in the developmental stage of spermatogenesis during which meiosis occurs. It is located in the seminiferous tubules of the testis.-Spermatogenesis:...

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