title: Leydig cell differentiation during the reproductive cycle of the seasonal breeder Camelus dromedarius: an ultrastructural analysis.
abstract: Spermatogenesis and Leydig cell development in the dromedary were analyzed at the ultrastructural level and correlated with fluctuations of testosterone synthesis during the mating and nonmating seasons. It was found that (1) spermatogenesis and diameter of the seminiferous tubules are dissociated from seasonal fluctuations of testosterone synthesis as they remain similar throughout the year; (2) the volume of the interstitial tissue and the rate of testosterone synthesis are correlated since both increase during the mating season and both diminish during the nonmating season; (3) during the mating season, reduction of the tubular smooth endoplasmic reticulum (SER) and proliferation of condensed SER correspond to the relatively high rate of testosterone synthesis by the 4-ene pathway; (4) during the mating season there is a drastic reduction of the SER and proliferation of myelin figures within the Leydig cells which disrupt at the end of their differentiation. During the nonmating season, testosterone synthesis is probably impaired only at the final stage of differentiation of the Leydig cell.
mesh_terms: D000818:Animals; D002162:Camelus / Q000033:anatomy & histology*; D003593:Cytoplasm / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D007985:Leydig Cells / Q000502:physiology / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D012098:Reproduction; D012621:Seasons; D012671:Seminiferous Tubules / Q000033:anatomy & histology; D013091:Spermatogenesis; D013737:Testis / Q000254:growth & development*; D013739:Testosterone / Q000096:biosynthesis
chemical_list: D013739:Testosterone