A spermatogonium is an intermediary male gametogonium

Gametogonium

A gametogonium is a germ cell that divides into gametocytes during gametogenesis. Male gametogonia are called spermatogonia, and female gametogonia are called oogonia....

 (a kind of germ cell

Germ cell

A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually. In many animals, the germ cells originate near the gut of an embryo and migrate to the developing gonads. There, they undergo cell division of two types, mitosis and meiosis, followed by...

) 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

Meiosis

Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....

 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

Spermiogenesis

Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is more or less circular cell containing a nucleus Golgi apparatus, centriole and mitochondria...

 to produce spermatozoa.

Source

This article includes material from Biology Online.