using the dogfish shark ( squalus acanthias ) in which there is a cystic mode of spermatogenesis and a topographic separation of different germ cell stages within the testis , we have obtained new information of general relevance on stage-related biochemical and morphological changes and have proposed a model in which steroids serve as parahormonal regulators of the spermatogenic progression .
C0037864
spermatogenesis
C0039597
testis