Ciclo reprodutivo do macho Ameiva ameiva (Squamata: Teiidae) baseado em seus aspectos morfológicos sazonais
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Data
2022-11-30
Autores
Maciel, Érica da Silva
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Universidade Estadual Paulista (Unesp)
Resumo
Ameiva ameiva é um lagarto amplamente distribuído no Brasil em áreas de Caatinga, Floresta Amazônica e Cerrado. É caracterizado por apresentar ciclo reprodutivo assazonal, porém, no que diz respeito à morfologia dos órgãos reprodutivos, o último trabalho foi realizado por Colli e Pinho (1997). Nós descrevemos a anatomia macroscópica e microscópica do sistema reprodutor a partir de 20 indivíduos machos coletados em uma área rural de Olímpia, município localizado no norte de São Paulo, Brasil. As estruturas analisadas foram os testículos, ductos condutores de espermatozoides, segmento sexual renal (SSR), hemipênis e corpos adiposos abdominais. Após analises macroscópicas e obtenção de fragmentos do testículo e da via seminífera para rotina histológica, dez secções de 5μm de cada região foram coradas com hematoxilia-eosina para descrição geral dos tecidos e com periodic acid-Schiff, Tricômico de Gomori e Picrossirius Red para as análises histoquímicas. Os hemipênis são monolobulados, alongados e cilíndricos, com uma face sulcada e outra face assulcada com ondulações transversais em sua porção mais distal. Em relação ao sistema de condução de sêmen de A. ameiva, foram descritos rede testicular, ducto eferente, epidídimo, ducto deferente cuja porção mais caudal, próxima à cloaca, apresenta uma dilatação formando a ampola. Os espermatozoides estão presentes em todas as regiões do ducto. Cada região mostrou características específicas em relação ao padrão morfológico e atividade do tecido epitelial. O epidídimo é mais enovelado, com epitélio 1.5 vezes mais alto quando comparado com o epitélio do ducto deferente. O SSR foi identificado no córtex da região ventral dos rins a partir da hipertrofia dos túbulos contorcidos distais, com função secretora para carboidratos neutros. O IGS foi maior nos animais coletados durante a primavera e o verão, em contraste com a gordura armazenada nos corpos adiposos, com maior quantidade no outono e inverno. A espermatogênese ocorreu durante o ano todo, com um aumento na altura do epitélio durante a primavera e o outono, sugerindo um período de maior atividade espermatogênica e regressão testicular parcial observada no inverno, já a espermiogênese foi maior no verão. O epitélio do SSR esteve mais hipertrófico entre o inverno-primavera e mais secretivo durante o verão (PAS positivo). No epidídimo, a massa espermática ocupou o ducto durante todas as estações, havendo uma diminuição no período de maior espermiogênese e no ducto deferente os espermatozoides estiveram em maiores quantidades durante a primavera, sugerindo o principal período de cópula 24 desses indivíduos. A análise do ciclo reprodutivo masculino de A. ameiva mostrou um padrão reprodutivo de ciclo sazonal para o nível populacional, com indivíduos semi-sincronizados e para o nível individual, ciclo reprodutivo contínuo. Os dados mostraram atividade reprodutiva mais intensa dos órgãos nos períodos de primavera e verão e menor atividade dos órgãos nos períodos de outono e inverno. Dados sobre lagartos neotropicais são escassos, sendo que esse estudo traz, pela primeira vez, informações importantes sobre a morfologia do sistema reprodutivo de A. ameiva, contribuindo para que demais trabalhos sobre o grupo sejam desenvolvidos.
Ameiva ameiva is a lizard widely distributed in Brazil in areas of Caatinga, Amazon Forest and Cerrado. It is characterized by having a continuous reproductive cycle, however, with regard to the morphology of reproductive organs, the last work was carried out by Colli and Pinho (1997). We describe the macroscopic and microscopic anatomy of the reproductive system from 20 male individuals collected in a rural area of Olímpia, a municipality located in the north of São Paulo, Brazil. The structures analyzed were the testes, sperm ducts, renal sexual segment of the kidney (SSK), hemipenis and fat bodies. After macroscopic analyzes and obtaining testis and seminiferous tract fragments for histological routine, ten 5μm sections from each region were stained with hematoxyly-eosin (HE) for general description of the tissues and with periodic acid-Schiff (PAS), Tricomic of Gomori and Picrossirius Red for histochemical analyses. The hemipenis are elongated and cylindrical, with one grooved face and the other grooved face with transversal undulations in its most distal portion. Regarding the semen conduction system of A. ameiva, rete testis, efferent duct, epididymis, vas deferens whose most caudal portion, close to the cloaca, presents a dilation forming the ampulla. Sperm are present in all regions of the duct. Each region showed specific characteristics in relation to the morphological pattern and activity of the epithelial tissue. The epididymis is more coiled, with epithelium 1.5 times higher when compared to the epithelium of the vas deferens. The SSK was identified in the cortex of the ventral region of the kidneys from the hypertrophy of the distal convoluted tubules, with a secretory function for neutral carbohydrates. GSI was higher in animals collected during spring and summer, in contrast to fat stored in adipose bodies, with greater amounts in autumn and winter. Spermatogenesis occurred throughout the year, with an increase in epithelium height during spring and autumn, suggesting a period of greater spermatogenic activity and testicular regression observed in winter, while spermiogenesis was greater in summer. The SSK epithelium was more hypertrophic between winter-spring and more secretive during summer (PAS positive). In the epididymis, the sperm mass occupied the duct during all seasons, with a decrease in the period of greater spermiogenesis and in the vas deferens spermatozoa were in greater quantities during spring, suggesting the main period of copulation for these individuals. The analysis of the male reproductive cycle of A. ameiva showed a continuous pattern containing variation, when individuals present fertility variations in some months of the 26 year. The data showed more intense reproductive activity of the organs in the spring and summer periods and less activity of the organs in the autumn and winter periods. Data on neotropical lizards are scarce, and this study brings, for the first time, important information about the morphology of the reproductive system of A. ameiva, contributing to the development of other works on the group.
Ameiva ameiva is a lizard widely distributed in Brazil in areas of Caatinga, Amazon Forest and Cerrado. It is characterized by having a continuous reproductive cycle, however, with regard to the morphology of reproductive organs, the last work was carried out by Colli and Pinho (1997). We describe the macroscopic and microscopic anatomy of the reproductive system from 20 male individuals collected in a rural area of Olímpia, a municipality located in the north of São Paulo, Brazil. The structures analyzed were the testes, sperm ducts, renal sexual segment of the kidney (SSK), hemipenis and fat bodies. After macroscopic analyzes and obtaining testis and seminiferous tract fragments for histological routine, ten 5μm sections from each region were stained with hematoxyly-eosin (HE) for general description of the tissues and with periodic acid-Schiff (PAS), Tricomic of Gomori and Picrossirius Red for histochemical analyses. The hemipenis are elongated and cylindrical, with one grooved face and the other grooved face with transversal undulations in its most distal portion. Regarding the semen conduction system of A. ameiva, rete testis, efferent duct, epididymis, vas deferens whose most caudal portion, close to the cloaca, presents a dilation forming the ampulla. Sperm are present in all regions of the duct. Each region showed specific characteristics in relation to the morphological pattern and activity of the epithelial tissue. The epididymis is more coiled, with epithelium 1.5 times higher when compared to the epithelium of the vas deferens. The SSK was identified in the cortex of the ventral region of the kidneys from the hypertrophy of the distal convoluted tubules, with a secretory function for neutral carbohydrates. GSI was higher in animals collected during spring and summer, in contrast to fat stored in adipose bodies, with greater amounts in autumn and winter. Spermatogenesis occurred throughout the year, with an increase in epithelium height during spring and autumn, suggesting a period of greater spermatogenic activity and testicular regression observed in winter, while spermiogenesis was greater in summer. The SSK epithelium was more hypertrophic between winter-spring and more secretive during summer (PAS positive). In the epididymis, the sperm mass occupied the duct during all seasons, with a decrease in the period of greater spermiogenesis and in the vas deferens spermatozoa were in greater quantities during spring, suggesting the main period of copulation for these individuals. The analysis of the male reproductive cycle of A. ameiva showed a continuous pattern containing variation, when individuals present fertility variations in some months of the 26 year. The data showed more intense reproductive activity of the organs in the spring and summer periods and less activity of the organs in the autumn and winter periods. Data on neotropical lizards are scarce, and this study brings, for the first time, important information about the morphology of the reproductive system of A. ameiva, contributing to the development of other works on the group.
Descrição
Palavras-chave
Espermatogênese, Neotropical, Reptilia, Segmento sexual renal, Spermatogenesis, Sexual segment of the kidney