Spermatocytogenesis is the male form of
gametocytogenesisand 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
spermatogoniaand 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
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 spermatocytes.
* [http://www.cvm.okstate.edu/instruction/mm_curr/histology/MR/HiMRP4.htm Histology at okstate.edu]
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