Reproductive functions in Desmodus rotundus: A comparison between seasons in a morphological context

Abstract

Reproductive seasonality in Neotropical bats has been assessed to the better understand their reproductive behavior. This knowledge is especially important for the control of Desmodus rotundus population as it is a transmitter of rabies virus. Therefore, we aimed to evaluate the functional activity of testis and epididymis of D. rotundus in dry and rainy seasons under a morphological approach. We observed an increase in tubular diameter and epithelial height of the seminiferous tubules during the rainy season. In the latter, additionally, stereological analysis of the testis showed increased proportion of seminiferous epithelium and reduced percentage of lumen. The sperm number in caput/corpus epididymis increased in rainy season, whereas sperm count and transit time were reduced in cauda region. These alterations were probably related to the recovery of epithelium activities after mating season in dry season. Despite altered nuclear and cytoplasm parameters of Leydig cells between seasons, the volume and number of these cells were constant. Moreover, no change in serum testosterone levels, daily sperm production, and apoptotic index were observed, which indicates that the reproductive pattern in D. rotundus does not change between seasons. Our study offers a baseline for the management of vampire bat population as an attempt to control rabies disease.

Seasonal evaluation of spermatogenesis of the hematophagous bat Desmodus rotundus in the Caatinga biome

“…The highest percentage of seminiferous epithelium observed in the rainy season led directly to the lowest percentage of lumen in the same season, which was similar to that observed in this species in an Atlantic forest region [28]. This indicates that the highest percentage of seminiferous epithelium observed in the rainy season is associated with a greater proliferation of germline cells in a period of greater food resources [17,29].…”

“…The average tubular diameter presented by the animals in this study was considerably larger when compared both to that found in other bat species and when compared to that found in the same species, in the Atlantic forest. The height of the seminiferous epithelium followed the same trend [ 15 , 16 , 17 , 24 , 28 ]. In addition, while most mammals usually have an average tubular diameter ranging from 180 to 300 μm [ 30 , 31 ], the value found here (432.17 μm) is the largest value so far reported.…”

Distribution pattern of ZO-1 and claudins in the epididymis of vampire bats

“…Authors have suggested that testosterone and other testicular factors might regulate the integrity of BEB, especially Cldn-1 expression. 7,14 A recent study reported that serum testosterone levels did not change in D. rotundus captured in both rainy and dry seasons, 26 indicating that other factors may be regulating the histological alterations observed here. In mink, low testosterone levels at the end of reproductive season did not modify BEB structure in contrast to the alterations found in its blood-testicular barrier.…”

“…Although D. rotundus bats were not evaluated monthly during rainy season by 26, this species exhibited intense activity of seminiferous epithelium in producing mature cells after the dry season that corresponds to their mating season, with consequent increase in sperm numbers in caput/corpus epididymis. 26 Thus, it is possible that lumicrine contents may differ between the rainy and dry season. Notably, the profile of luminal fluid content display substantial segmentto-segment variations, 44 and these differences may dramatically change during mating season.…”

“…25 Despite alterations in testis morphometry have been recently described in D. rotundus captured in rainy and dry seasons, no alteration was observed in sperm and testosterone production. 26 It is known that testosterone might play an important role in the regulation of TJs, with possible regulation mechanism of Cldn-1 in the initial segment of the rat epididymis. 14 Notwithstanding, there is scarce information concerning the influence of environmental variations in the TJ organization within the BEB of wild animals.…”