The spermatogenic cycle in the silver fox (Vulpes vulpes): frequency of the different stages prior to and during the breeding season

In the silver fos the cycle of the seminiferous epithelium could be classif ied into eight characteristic stages defined on the basis of different, wel l-defined cell associations. The main criteria for the staging were the typ e of spermatogonia, the appearance of primary spermatocytes, the occurrence of meiotic figures and secondary spermatocytes and the shape and location of spermatids. In come cases more than one stage could be found within the same transverse tubular section. The average frequency of stages I to VIII was 25.2, 8.2, 9.0, 4.9, 16.2, 8.3, 10.7 and 17.5%, respectively. No signif icant difference was found between individuals sampled before and at the be ginning and end of the breeding season. However , late in the season the mi gration of old spermatids and release of spermatozoa tended to be somewhat retarded, causing a slight increase in the duration and frequency of the la st two stages oi the cycle.