Testicular characterization and spermatogenesis of the hematophagous bat Diphylla ecaudata

Abstract

Diphylla ecaudata is a hematophagous bat endemic of South America, with food preference for bird blood. Given the lack of information about the reproductive activity of this species, this study aimed to describe the testicular morphology and histomorphometry of D. ecaudata in order to understand its reproductive biology, specially spermatogenesis. The animals were collected in Lajes city, Rio Grande do Norte, Brazil. Following euthanasia, the testes were histologically processed for morphological, morphometric, ultrastructural and immunohistochemical analyses. Their average body weight was 24.64g, with a gonadosomatic index of 0.49%, tubulesomatic index of 0.47%, and a total of 32.20m of seminiferous tubules per gram of testis. The pre-meiotic, meiotic, and post-meiotic phases accounted for 56.20%, 9.30%, and 34.50% of the seminiferous epithelium cycle, respectively. The ultrastructure of spermiogenesis was similar to that described in other mammals and the perforatorium was not observed in the sperm. Androgen receptors were detected in Sertoli cell nuclei and Leydig cell cytoplasm, while aromatase enzyme was detected only in Sertoli cell nuclei. FGF2 and BCL-2 activities were detected in the cytoplasm of zygotene and pachytene primary spermatocytes, as well as round and elongated spermatids. D. ecaudata showed testicular pattern similar to other mammals and characteristics common to other bat species. This species stood out for its high efficiency of Sertoli cells, which presented high capacity to support germ cells, besides the highest sperm production rates among those already recorded. This study is the first step towards the knowledge of D. ecaudata reproduction and the first description of its spermatogenesis.

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

“…The number of positive cells per tubular cross section for each antibody was quantified in relation to the number of cells without immunostaining, in an area of approximately 40,000 μm 2 . The following formula was used: [(number of marked cells / number of unmarked cells) / number of analyzed sections] [ 15 ].…”

“…Digital images were obtained using a light-field photomicroscope (Olympus BX-50 or BEL Bio2/3 Eurekam 5.0) and analyzed based on testicular stereology, using the Image-Pro Plus ® software. The volumetric proportions of all components of the seminiferous tubule (tunica propria, seminiferous epithelium, and lumen), intertubule and tunica albuginea were determined after counting 3,520 intersection points, per animal, in 10 square grids randomly placed over the digital images (100x magnification) [ 15 , 16 ].…”

“…The volume of each intertubular component in the testicular parenchyma was calculated by the following formula: (percentage of each component in the testis x gonadal weight) / 100. The values were expressed in μL [ 15 , 16 , 18 ]. Since the mammalian testis density is around 1 [ 19 ], its weight was considered equal to the volume.…”

“…Both testes were weighed after fixation, using an analytical balance (BEL M214AIH). The gonadosomatic index (GSI) was calculated by dividing the testes weight by body weight and PLOS ONE multiplying by 100, to quantify the weight proportion of the testicles with respect to the total body mass [15].…”

“…The seminiferous tubule length (STL, in meters) per testis was estimated as follows: STL = STV/ πR 2 (πR 2 = tubule area; R = tubular diameter/2). The STL was divided by the testicular weight to calculate the length of the seminiferous tubules per gram of testis (STL/g), to allow comparisons between different species [15][16][17].…”