Morfologia do útero e ovários de Artibeus planirostris (Phyllostomidae: Chiroptera) durante as fases do ciclo reprodutivo
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Data
2016-02-25
Autores
Caun, Dianelli Lisboa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Apesar das diferentes estratégias reprodutivas apresentadas pelos morcegos, relativamente pouca atenção tem sido dada aos estudos morfológicos das estruturas reprodutivas nesses animais. Com o intuito de gerar informações que propiciem uma descrição mais detalhada dos aspectos reprodutivos em Chiroptera, o objetivo do presente estudo foi descrever a morfologia dos órgãos reprodutivos (útero e ovários) das fêmeas de Artibeus planirostris (Phyllostomidae) durante quatro fases do ciclo reprodutivo e analisar o processo de foliculogênese. As fêmeas de A. planirostris possuem um útero simples de histologia semelhante ao padrão geral dos mamíferos, com a parede uterina sendo composta por três camadas, na qual a mais interna, o endométrio, demonstrou um processo de descamação e necrose, que ao ser associada com sangramento, caracteriza a menstruação. Artibeus planirostris produz apenas um filhote por gestação e exibe um padrão poliéstrico, evidenciado pela captura de fêmeas concomitantemente grávidas e lactantes, demonstrando a existência de um estro pós-parto. Os ovários de A. planirostris, apresentaram uma polaridade aparente, com os folículos primordiais restritos a uma zona localizada em apenas um lado do ovário, a partir da qual os folículos são recrutados para posterior crescimento e desenvolvimento. Ambos os ovários são funcionais, confirmados pela presença do corpo lúteo, mas constatamos que eles não podem ser considerados bilateralmente simétricos, uma vez que o corpo lúteo foi encontrado preferencialmente no ovário esquerdo (76,2%). Os ovários durante a gravidez apresentam diferenças significativas entre si, evidenciando um processo de regressão por parte do ovário sem corpo lúteo, que apresenta grandes quantidades de folículos atrésicos, e valores de diâmetro, área e volume significativamente menores do que o ovário que ovulou (com corpo lúteo). Quanto ao processo de foliculogênese, A. planirostris segue o padrão básico dos mamíferos e outros morcegos, tendo início com o recrutamento de folículos primordiais, visando seu crescimento e desenvolvimento, podendo se tornar um folículo maduro (de Graaf) ou morrer por um processo de atresia. Com esses resultados, fornecemos detalhes sobre o ciclo reprodutivo de A. planirostris, evidenciando características reprodutivas típicas dessa espécie.
Despite the many reproductive strategies employed by bats, there is not enough attention being given to the morphological studies of reproductive structures of the Chiroptera. Aiming to generate informations that enable a more detailed explanation of the reproductive aspects of Chiroptera, the purpose of this study is to describe the morphology of the reproductive organs (uterus and ovaries) of female Artibeus planirostris (Phyllostomidae) during four phases of the reproductive cycle and analyse the folliculogenesis. The A. planirostis female has a simple uterus, histologically similar to the mammalian general pattern, uterine wall formed by three layers, of which, the inner layer, the endometrium, has showed process of necrosis and scaling that, when combined with bleeding, typifies menstruation. Artibeus planirostis produces only one offspring per gestation and presents a poliestric pattern, corroborated by the capture of females concomitantly pregnant and lactating, desmonstrating the existence of a postpartum estrus. The ovaries of A. planirostis showed an apparent polarity, with the primary follicles restricted to an area located in only one side of the ovary, from which the follicles are recruited to the consequent growth and development. Both ovaries are functional, confirmed by the presence of the corpus luteum and it was found, however, that they can not be considered bilaterally simetrical, for the corpus luteum was predominantly found in the left ovary (76,2%). The ovaries, during pregnancy, showed significant differences among each other, evincing a regression process of the ovary that did not present corpus luteum and showing great quantity of atretic follicles, and with diameter, area and volume significantly smaller than the ovary which presented corpus luteum, i.e., which has ovulated. As for the folliculogenesis process, A. planirostis follows the basic mammalian pattern as well as other bats, starting with primary follicle recruiting, growing and developing it, and enabling it to become a mature follicle (graafian foliclle) or dying of a process of atresia. With such results, we provide details on the reproductive cycle of A. planirostis, evincing typical reproductive characteristics for this species.
Despite the many reproductive strategies employed by bats, there is not enough attention being given to the morphological studies of reproductive structures of the Chiroptera. Aiming to generate informations that enable a more detailed explanation of the reproductive aspects of Chiroptera, the purpose of this study is to describe the morphology of the reproductive organs (uterus and ovaries) of female Artibeus planirostris (Phyllostomidae) during four phases of the reproductive cycle and analyse the folliculogenesis. The A. planirostis female has a simple uterus, histologically similar to the mammalian general pattern, uterine wall formed by three layers, of which, the inner layer, the endometrium, has showed process of necrosis and scaling that, when combined with bleeding, typifies menstruation. Artibeus planirostis produces only one offspring per gestation and presents a poliestric pattern, corroborated by the capture of females concomitantly pregnant and lactating, desmonstrating the existence of a postpartum estrus. The ovaries of A. planirostis showed an apparent polarity, with the primary follicles restricted to an area located in only one side of the ovary, from which the follicles are recruited to the consequent growth and development. Both ovaries are functional, confirmed by the presence of the corpus luteum and it was found, however, that they can not be considered bilaterally simetrical, for the corpus luteum was predominantly found in the left ovary (76,2%). The ovaries, during pregnancy, showed significant differences among each other, evincing a regression process of the ovary that did not present corpus luteum and showing great quantity of atretic follicles, and with diameter, area and volume significantly smaller than the ovary which presented corpus luteum, i.e., which has ovulated. As for the folliculogenesis process, A. planirostis follows the basic mammalian pattern as well as other bats, starting with primary follicle recruiting, growing and developing it, and enabling it to become a mature follicle (graafian foliclle) or dying of a process of atresia. With such results, we provide details on the reproductive cycle of A. planirostis, evincing typical reproductive characteristics for this species.
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Palavras-chave
Phyllostomidae, Ciclo reprodutivo, Menstruação, Ovário polarizado, Foliculogênese, Phyllostomidae, Reproductive cycle, Menstruation, Polaryzed ovary, Folliculogenesis