Mechanisms of prolonged sperm storage in female bats

Abstract

Prolonged sperm storage is an adaptation to the reproductive cycle that is most highly developed in microchiroptera, where sperm may be stored up to ~198 days and still retain fertilizing capacity. The aim of this review is to describe the mechanism and molecules necessary for sperm to become efficiently stored in the female genital tract. Perpendicular orientation of sperm with their head towards the reproductive tract epithelium are characterized in all sperm-storing bat species so far investigated, suggesting that such relationships are an integral part of the mechanism of prolonged storage of sperm. Recent study suggests that the ultimate controls of the mechanism underlying sperm storage are hormonal. It has been demonstrated that sperm-storing female bats contain a high circulating level of androgen during the period of sperm storage. It is suggested that androgen creates a unique microenvironment that facilitates prolonged sperm storage. The identification of the specific molecules responsible for prolonged sperm storage may suggest a mechanism to keep sperm viable for a prolonged period for use in assisted reproductive techniques. © 2011 Nova Science Publishers, Inc. All rights reserved.