Biologia reprodutiva e dosagem hormonal de jurará (Kinosternon scorpioides – Linnaeus-1766): estudo em ambiente natural no município de São Bento – Baixada maranhense

Abstract

In the State of Maranhão, in the lowland region of Maranhão, is found in the in the wild fauna the reptile Kinosternon scorpioides, a freshwater chelonian popularly known as ―jurará‖. It has social, economic and environmental value for the riverside population in the city of São Bento. This study focuses its reproductive biologic characteristics based on its natural environment, in order to ensure its preservation and to establish plans of reproductive management and sustainable use of the specie. It has as objective to characterize morphologically the male jurará’s reproductive organs and to verify its hormone levels in the natural environment in two periods of the year: the rainy and the dry, so that we can verify if there is reproductive seasonality. Twenty adult animals had their reproductive organs ultra-structurally characterized by light microscopy, scanning electron microscopy and transmission electron microscopy; and testosterone levels were dosed by radioimmunoassay. Morphologically, the testicles are covered by the tunica albuginea, composed of seminiferous tubules, and surrounded by a basal lamina, with proliferation of germ and support cells during the rainy season. In the dry season there is a clear decrease in the spermatogenic activity. The epididymis are divided into rete testis, efferent ducts and epididymal duct. They present, during the rainy season, a pseudostratified and stereociliated type of epithelium; while in the dry seasons it is characterized by simple, cubic and non-ciliated cells. The deferent ducts are continuous to the epididymis, and revested by pseudostratified cylindric epithelium, with differences in the structural plane of the gonads evaluated between the seasons. The morphometry of the tubular and luminal diameter and epithelial height of the testis and of the epididymis showed cyclic moments over the studied periods, with the highest means in the rainy season, coinciding with the reproductive period. However, the deferent duct showed these same measures in the dry season, which may be related to spem stocking. The testosterone showed levels of 937,74 ng/ml in the rainy season, and 741,61 ng/ml in the dry season, with significant difference between them. Thus, it is concluded that during the studied periods, the presented data suggests that there is seasonality in the jurará in natural environment.