Evaluation of the Cell Population of the Seminiferous Epithelium and Spermatic Indexes of the Bat Sturnira lilium (Chiroptera: Phyllostomidae)

Abstract

Due to the scarcity of information about patterns of spermatogenesis in bats, this study aimed to provide information on the testicular activity of the bat Sturnira lilium along the annual seasons. Thus, a series of morphometrical and stereological analyses were made using the testes of adult S. lilium in order to achieve a better understanding of the sperm production dynamics. Light and transmission electron microscopy analyses were performed in testicular fragments of animals captured during dry and rainy seasons. The testes followed the pattern of organization described for other mammals, and there were no morphological differences between organs collected either in dry or in rainy seasons. Each tubular cross-section in stage 1 was made of 0.5 type-A spermatogonia, 4.4 primary spermatocytes in preleptotene/leptotene, 3.7 in zygotene, 11.9 in pachytene, 35.6 round spermatids and 8.5 Sertoli cells. The mitotic and meiotic indexes were 15.4 and 2.9 cells, respectively, while the spermatogenesis yield was 68.7 cells. The testicular sperm reserves was 37.61×106 cells, and daily sperm production per gram of testis averaged 209.68×106 cells, both highest averages occurring in the rainy season. S. lilium male bats have a continuous reproductive pattern, high spermatogenesis yield and low support capacity by the Sertoli cells.

The spermatogenic process of the common vampire bat Desmodus rotundus under a histomorphometric view

“…Stage 1 was the most frequent, which is in accordance with the observed in several mammals [10, 11, 22, 23, 30, 36–39]. Unlike M .…”

“…lilium , D . rotundus testes showed primary spermatocytes in zygotene at stage 2, similarly the pattern described in other mammalian orders [10, 11, 22, 26, 40–41]. …”

“…lilium [12] and M . molossus [10], while the percentages of tunica propria, seminiferous epithelium and lumen found for vampire bats were similar to that observed in M .…”

“…molossus [10]. The tubular diameter and the height of seminiferous epithelium were larger than observed in other bats [10, 12]. …”

“…Recent studies on the spermatogenic process in other Chiropteran species have shown interesting characteristics of these animals when compared to other mammals, such as high levels of sperm production and short spermatogenical cycle [10–12], which has given a prominent role to bats regarding their reproductive capacity.…”