Apoptosi nella dinamica follicolare della specie equina

Summary Mares have a seasonal breeding with prolonged transition periods. During the seasonal anaestrous, endogenous opioids peptides are invol- ved in the suppression of gonadotropin secretion. Furthermore a role of endogenous opioid peptides in promoting cell death has been reported and neuronal apoptosis has been associated with abnormal intracellular calcium levels; because seasonality is limiting in reproductive manage- ment and in the establishment of assisted reproductive programs, with this study we analyze: the occurrence of apoptosis in the mare's ovary as a mechanism underlying the seasonal modifications of follicular de- velopment or atresia during the year; the effects of Naloxone (an opioid antagonist) and calcium administration on follicular develop- ment and apoptosis in anaestrous mares: the relationship among granu- losa cell apoptosis, initial cumulus morphology, maturation rate in vitro and pronuclear formation after intracytoplasmic sperm injection (ICSI). The results obtained suggest that apoptosis is the basic process con- trolling follicular atresia in the mare and may provide the mechanism underlying seasonal modifications of ovarian activity, furthermore Na- loxone and calcium treatment induces, in anaestrous mares, the deve- lopment of new viable follicles. Normal fertilization is observed in oocytes issuing from expanded cumulus, both from apoptotic and non apoptotic follicles, whereas oocytes issuing from compact cumulus we- re fertilized only when recovered from apoptotic follicles.