SEASONAL-VARIATION IN OVARIAN HISTOLOGY OF THE VIVIPAROUS LIZARD SCELOPORUS-TORQUATUS-TORQUATUS

Changes in ovarian histology during the reproductive cycle of the vivi parous lizard Sceloporus torquatus torquatus are described. In general , the variation in follicular histology observed during the seasonal c ycle is similar to that of other lizards. Sceloporus t. torquatus exhi bits a cycle in which small, previtellogenic follicles exist in the ov ary from December to August. Vitellogenesis occurs between September a nd November, followed by ovulation from late November to early Decembe r. Parturition occurs the following spring. After ovulation, the remai ning follicular cells form the corpus luteum and luteolysis did not oc cur until April-May. Follicular atresia is commonly observed in previt ellogenic follicles with polymorphic granulosa, but occurs less freque ntly in follicles during late vitellogenesis. There are two germinal b eds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are obse rved in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. (C) 1995 Wiley-Liss, Inc.