Analysis of Spermatogenesis Using an Eel Model

Spermatogenesis is an indispensable process for the continuity of life. The process of spermatogenesis is very complex; it begins with spermatogonial renewal, then proceeds to proliferation of spermatogonia towards meiosis, two meiotic reduction divisions and spermiogenesis, during which the haploid spermatid develops into a spermatozoa. After spermiogenesis, non-functional sperm pass the process of sperm maturation and then become mature spermatozoa, fully capable of vigorous motility and fertilization. These processes are mainly controlled by sex steroid hormones. Spermatogonial renewal is controlled by estrogen; estradiol-17β (E2) through the expression of platelet-derived endothelial cell growth factor (PD-ECGF). The proliferation of spermatogonia toward meiosis is initiated by androgen; 11-ketotestosterone (11-KT) produced by FSH stimulation. 11-KT prevents the expression of anti-Müllerian hormone (AMH), which functions to inhibit proliferation of spermatogonia and induce expression of activin B, which functions in the induction of spermatogonial proliferation. Meiosis is induced by progestin; 17α,20β-dihydroxy-4-pregnen-3-one (DHP) through the action of trypsin. DHP also regulates the sperm maturation through the regulation of seminal plasma pH.