Kinosternon scorpioides , popularly known as scorpion mud turtle (jurará in Brazil), is a fresh water species. There is little information about its reproduction and the present study aims to morphologically characterize the reproductive organs of male K.scorpioides bred in captivity in two seasons of the year. The reproductive tracts of adult animals under went macroscopic ultrastructural analysis of the lumen, as well as scanning electron and transmission microscopy. Macroscopically, the male genital organs consist of a pair of testicles, epididymis, the vas deferens and a penis. Testicles, epididymis and deferents ducts were characterized by reproductive activity during the rainy season and reproductive inactivity in the dry period. The morphometry regarding the tubular and luminal diameter and epithelial height of the testicles, epididymis and deferents ducts showed changes along the studied periods. The rainy season presented higher averages than the dry period. The penis did not show any changes during both periods. It was concluded that K. scorpioides exhibits reproductive seasonality.

Background: The developmental biology of K. scorpioides is described, based on the phenotype. This species is important for the flora because they are excellent seed disseminators. In addition, basic embryological information is not yet fully clarified, and this research provides unprecedented information on the chelonian embryology of the Amazonian fauna. Methods: Females were monitored throughout the reproductive cycle, by video monitoring, to identify nests and the presence of newly laid eggs. At regular weekly intervals, embryo samples were collected fixed in a 4% paraformol solution and preserved in 70% alcohol. For the embryonic characterization we used a stereomicroscope and the scanning electron microscopy method. Results: We describe 15 embryonic stages for a 15-week (105-day) incubation cycle. Only at 42 days (6th week) was the morphological characterization of a chelonian observed and at the 12th week (Stage XII) the phenotypic characterization of the species kinosternon scorpioides. Conclusions: In view of the evidence, we found that these phases are similar to the other turtles, with structural variations in the appearance and disappearance of structures due to the specific characteristics for the species.

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