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

This study was aimed to characterize the spermatogenic process and its seasonal variation in Desmodus rotundus, in the Caatinga biome, a water-limited ecosystem, with marked water restriction during most of the year. Collections of adult animals were performed during the dry and rainy seasons, and after euthanasia, their testes were processed histologically to perform morphological, morphometric, ultrastructural and immunohistochemical analyzes. The percentage of seminiferous epithelium, number of Leydig cells per gram of testis, and population of Sertoli cells and A-type spermatogonia presented by D. rotundus were significantly higher in the rainy season, while the percentage of lumen, mitotic index, support capacity performed by Sertoli cells, and overall yield of spermatogenesis were higher in the dry season. The ultrastructure of spermatogenesis was similar to that described in other mammals, and the immunohistochemical analysis revealed activity of the aromatase enzyme in Sertoli cells, Leydig cells, spermatocytes and spermatids, as well as the presence of androgen receptors in Sertoli cells and Leydig cells. FGF2 activity was detected in primary spermatocytes in zygotene and pachytene, as well as secondary spermatocytes and rounded and elongated spermatids, while the BCL-2 protein was expressed in primary spermatocytes in zygotene and pachytene, secondary spermatocytes, and rounded spermatids. The activity of these molecules was similar in both seasons, and associated with the morphometric findings, indicates maintenance in the integrity of the seminiferous epithelium throughout the year. The seasonal study of D. rotundus spermatogenesis indicates a continuous spermatogenesis pattern and suggests a greater production of spermatozoa in the rainy season in the Caatinga biome.