The final stage of spermatogenesis in which the spermatids differentiate into mature, motile spermatozoa.
The spermiogenesis is generally composed of four major stages:
(1) Golgi phase - the spermatid starts to form a head and an axoneme while its DNA undergoes packaging, becoming highly condensed.
(2) Cap phase - formation of the acrosomal cap
(3) Acrosomal phase - one of the centrioles of the spermatid elongates to become the tail.
(4) Maturation phase - the remaining cytoplasm and organelles are removed by phagocytosis of Sertoli cells. The Sertoli cells also release the now elongated, non-motile spermatids into the lumen of the seminiferous tubules, to be transported to the epididymis where they will become motile spermatozoa.
See also: spermatogenesis, spermiation