Spermatogenesis in testis primary cell cultures of the tilapia (Oreochromis niloticus)

Spermatogenesis in vertebrates is controlled by endocrine and paracrine factors and involves the communication between somatic and germ line cells. To elucidate some of the relevant factors in the complicated molecular control processes, we established an in vitro test system using primary cultures of tilapia (Oreochromis niloticus) testis cells. The cultures were enriched for germ line cells and Sertoli cells and largely depleted of spermatozoa. By staining the cells with propidium iodide and carboxyfluorescein succinimidyl ester (CFSE), different cell populations could be identified cytologically and, in addition, quantified by flow cytometry. Cells that had gone through one or more divisions could be identified unequivocally based on their CFSE staining intensity. In parallel cultures maintained for up to 16 days in the presence of 11-ketotestosterone (KT), insulin-like growth factor I (IGF), and/or human chorionic gonadotropin (hCG) the initiation of meiotic and mitotic divisions was monitored. Although KT was important for the initiation of meiosis, spermatogonial mitotic divisions between 10 days and 16 days of culture were promoted by IGF and/or hCG in the presence of KT. These results illustrate the potential of the established in vitro test system for the analysis of the molecular control mechanisms of spermatogenesis. (c) 2005 Wiley-Liss, Inc.