ABSTRACT
Several species of the family Vespertilionidae store spermatozoa for prolonged periods prior to ovulation, but the reproductive strategy used by Myotis capaccinii remains unknown. Reproductive cycle of Myotis capaccinii has been determined using macroscopic and microscopic examinations on two captured bats in spring and one male and one female reared in a flight cage during winter. Microscopic slides prepared from one male collected in late July showed spermatids indicating that spermatogenesis develops in summer. Estimation of the volume of testes and epididymis based on photographs taken on weekly intervals during late summer until late winter in male, M. capaccinii shows that the rate of epididymis to testes volume increases by more than one order of magnitude from late summer until late winter. Microscopic slides prepared from this bat indicate that decapacitated spermatozoa are packed in the tubules in the epididymis in late winter