Reproductive cycle in Pipistrellus kuhlii (Chiroptera,Vespertilionidae) in western Iran

The reproductive cycle of male and female Pipistrellus kuhlii are described. Sexual activity is based on the degree of testicular and cauda epididymal development and on histological examination of both male and female reproductive organs. During the study spermatogenesis took place during summer and spermatozoa were released from the testis in August and September. Although no more spermatozoa were produced during late summer and early autumn, they continued to be stored in the cauda epididymides for winter. Endometrial sperm storage in the uterus of females in mid-December together with packing and perpendicular orientation of spermatozoa toward the endometrum indicate that Pipistrellus kuhlii mate in winter and store spermatozoa until spring when the fertilization takes place. This study indicates that the reproductive cycle of Pipistrellus kuhlii involves asynchrony between primary and secondary sexual function which is typical of vespertilionid bats inhabiting temperate latitude.