RESUMO
Males of the bat Eptesicus furinalis show at least one process of testicular regression, in which the testes regress and temporarily interrupt the production of sperm, during its annual reproductive cycle. As the process of spermatogenesis is under hormonal control, mainly of pituitary and androgen hormones, our aim was to analyze the morphological variations and the hormonal control of the testes of E. furinalis during the four phases of its reproductive cycle. Testes of 18 adult males, divided into four sample groups (active, regressing, regressed, and recrudescence phases), were submitted to morphological, morphometric, and immunohistochemical analyzes. The results demonstrate that the processes of testicular regression and recrudescence of E. furinalis are under the control of pituitary, androgen and estrogen hormones. The regulation is exerted mainly through the activation and cross signaling of AR and FSHR in Sertoli cells and of LHR in Leydig cells. The testicular regression appears to be activated by an inhibition/reduction of AR expression in Sertoli cells, which inhibits the proliferation and differentiation of new spermatogonia and causes the deactivation of spermatogenesis. Conversely, the testicular recrudescence occurs by the increasing of the expression of LHR in Leydig cells, and AR and FSHR in Sertoli cells, which reactivates the testicular production of androgens and estrogens, the proliferation of spermatogonia and restarts the spermatogenesis.
RESUMO
Molossus molossus is an insectivorous molossid bat that is important in the control of nocturnal insects. It is the nominal and the most representative species of the family. However, there are few studies about its reproduction. Thus, this study aimed to evaluate variations of its female reproductive organs during the different reproductive phases. Twenty adult females, divided into four sample groups (non-reproductive, early and advanced pregnancy and lactation), were submitted to morphological and morphometric analyses. Results show that the female reproductive system of M. molossus is composed of ovaries, a short bicornuate uterus, slightly convoluted uterine tubes and vagina. The system presents a distinct morphofunctional asymmetry, with a marked dextro-dominance. The right ovaries of all analyzed groups (NON, P1, P2, and LAC) showed follicles at different stages of development, a large number of interstitial glands and a small, but persistent corpus luteum. Ovulation is simple, unilateral and preferential, occurring exclusively in the right ovary. Follicular development in the left ovary usually does not pass the secondary stage. Implantation is fundic and preferential, occurring exclusively in the right uterine horn. The placenta is formed with two distinct chorioallantoic portions, one diffuse endotheliochorial, which covers the entire uterine cavity and regresses in the final stages of pregnancy, and the principal discoidal hemochorial portion, formed in the implantation site. The uterine cervix presents a pseudostratified epithelium, while the vagina has a little keratinized stratified epithelium, which does not accentually vary in the different reproductive stages, but can disrupt and shed in some cases.
Assuntos
Quirópteros , Gravidez , Animais , Feminino , Quirópteros/anatomia & histologia , Útero , Reprodução/fisiologia , Placenta , VaginaRESUMO
Artibeus lituratus is one of the most well-known bat species in the Neotropics, probably due to its high abundance and the ability to inhabit urban areas. It plays an important ecological role in the ecosystem due to its ability to disperse seeds, which contributes to the regeneration of degraded areas. Actually, the species has been used as an important experimental model for ecotoxicological studies of the impact of pesticides on male reproduction. Despite that, the reproductive pattern of A. lituratus is still controversial due to inconsistent descriptions of the reproductive cycle. Thus, the aim of the present work was to evaluate the annual variations of the testicular parameters and sperm quality of A. lituratus and analyze their responses to annual variations in abiotic factors in the Cerrado area in Brazil. Testes of five specimens were collected each month for one year (12 sample groups) and submitted to histological, morphometric, and immunohistochemical analyses. Analyses of the sperm quality were also performed. Results demonstrate that A. lituratus presents a continuously active process of spermatogenesis throughout the year, with two significant peaks in spermatogenic production (September-October and March), which indicates a bimodal polyestric pattern of reproduction. These reproductive peaks seem to be related to an increase in proliferation and, consequently, in the number of spermatogonia. Conversely, seasonal variations in testicular parameters are correlated with annual fluctuations in rainfall and photoperiod but not with temperature. In general, the species presents smaller spermatogenic indexes with a similar sperm quantity and quality to other bat species.