The interactions between spermatozoa and uterine epithelium in the hibernating bat, pipistrellus kuhli natt

Evidence of androgen-dependent sperm storage in female reproductive tract of Scotophilus heathi

The aim of present study was to investigate the role of androgen in sperm storage in the female genital tract of Scotophilus heathi. Spermatozoa were observed in the distal part of oviduct and utero-tubal junction of all the female bats collected between January and early March. Increase in circulating testosterone level coincided with the arrangement of sperm with their head oriented towards the epithelial lining of reproductive tract. Immunocytochemical and Western blot analysis revealed the presence of androgen receptor (AR) only in the distal part of the oviduct and utero-tubal junction, the site of sperm storage. Localization of AR in the cytoplasm of luminal epithelial cells in utero-tubal junction of S. heathi suggests non-genomic action of androgen at the site of sperm storage. Further study showed the presence of intense immunoreactivity of androgen binding protein (ABP) in the glandular epithelial cells of utero-tubal junction. It is hypothesized that androgen creates a unique microenvironment e.g. secretion of ABP within lumen of utero-tubal junction which helps to store spermatozoa for prolonged period in the female genital tract of S. heathi.

Fine structure of the neck of epididymal spermatozoa of Schreiber's long-fingered bat (Chiroptera: Mammalia)

The structure of the spermatozoon of the long-fingered bat (Miniopterus schreibersii) was studied using transmission electron microscopy. The neck is characterized by two asymmetrically arranged features that allow the orientation of sections in different planes and therefore aid the interpretation of the structure. There are six segmented columns, two major and four minor, in the anterior 79% of the neck, and it is only posterior to this that the major columns split. One major column is associated with doublets 9, 1, and 2, and the other major column, with doublets 5 and 6. The proximal centriole is surrounded by the capitulum and segmented columns, and the distal centriole persists and is apparent in both longitudinal and transverse sections. The central pair of microtubules pass through the distal centriole and terminate at the proximal centriole. A line drawn through the two central microtubules divides the head into left and right halves. Development of the neck begins during early spermiogenesis at which time the two centrioles are associated with the production of the capitulum, segmented columns, and axoneme complex.