THE REGULATION OF THE REPRODUCTIVE CYCLE OF THE FEMALE LIZARD, LACERTA SICULA SICULA RAF

SUMMARY In adult females of Lacerta sicula sicula Raf. the reproductive cycle of a small population living in the wild has been correlated with seasonal fluctuations in environmental meteorological conditions. In the spring, the ovary begins to develop at a time when both temperature and photoperiod are increasing. The ovarian activity abruptly decreases in July even though the temperature is still high, the photo-period is still lengthy, and the food supply is plentiful. This supports the view that gonadal tissues become «insensitive» to environmental photo-thermal stimulation because an endogenous «refractory» period intervenes. This prevents any further oocytes maturation after the breeding season. The refractory state lasts until January-February, but from October some oocytes begin to grow though they never reach the vitellogenic phase. This growth continues, at a very low pace, throughout the autumn and winter. Only in the following spring do vitellogenic processes appear. Maintenance of adult femal...