Reproductive cycles of neotropical boid snakes evaluated by ultrasound.

Snakes have increasingly been bred as pets around the world. Few studies have addressed the reproduction of boid snakes, and no study has addressed their reproductive cycles in captivity. Thus, this paper describes the reproductive aspects of Brazilian boids in captivity. We used ultrasonography to characterize the reproductive cycle of four boid species in captivity in the Southern Hemisphere: the anaconda (Eunectes murinus), the red-tailed boa (Boa constrictor constrictor), the Amazon tree boa (Corallus hortulanus), and the rainbow boa (Epicrates cenchria). Nonvitellogenic follicles occurred from January to December in anaconda and red-tailed boa and for a shorter period from September to February in Amazon tree boa and from January to May in rainbow boa. Vitellogenesis occurred from late June to late March in E. murinus in year-round (12 months), from March to March in Amazon tree boa, from late September to late March in red-tailed boa, and from late March to late September in rainbow boa. Mating occurred from late March to late September in red-tailed boa and rainbow boa and from late September to late March in Amazon tree boa. No mating was observed in anacondas, but a female probably underwent parthenogenesis. Births occurred in July in anaconda and in March to July in Amazon tree boa and from December to March in red-tailed boa and rainbow boa. In males, increases in testicular size were associated with the mating season. Ultrasonography proved to be a safe and noninvasive technique to study the reproductive cycle of giant snakes in captivity.

Avaliação ultrassonográfica do aparelho reprodutor em serpentes vivíparas da família Boidae / Ultrasonographic evaluation of reproductive tract in viviparous snakes Boidae family

A reprodução faz parte do ciclo de vida dos animais permitindo a perpetuação e a conservação das espécies. Em serpentes, existe uma escassez de informações técnicas a respeito do ciclo reprodutivo. Este estudo teve o objetivo de avaliar o aparelho reprodutivo por meio da ultrassonografia em serpentes vivíparas cativas da família Boidae, permitindo diagnosticar as diferentes fases reprodutivas. Foram avaliadas ultrassonograficamente onze serpentes adultas de quatro espécies da família Boidae: Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus e Epicrates cenchria pertencentes ao acervo do Museu Biológico do Instituto Butantan, São Paulo Brasil. Para a avaliação ultrassonográfica, as serpentes foram contidas fisicamente com gancho herpetológico e depois manualmente por aproximadamente 15 minutos. A avaliação foi feita aplicando-se gel acústico sobre a pele e posicionando o transdutor na linha lateral-ventral direita e esquerda, em região medial do corpo em sentido crânio-caudal. O exame ultrassonográfico permitiu avaliar todo o ciclo reprodutivo nas serpentes. Nas avaliações ultrassonográficas das fêmeas pode-se definir as fases de desenvolvimento ovariano e ovidutal. Os folículos ovarianos durante a fase pré-vitelogênica foram visualizados como homogêneos e anecogênicos, em forma de "cacho de uva". Já na fase vitelogênica, os folículos estavam maiores e mais ecogênicos seguidos uns dos outros, como um "colar de pérolas". Quando não houve cópula, os folículos foram reabsorvidos dentro do ovário retornando a fase pré-vitelogênica. Na fase pós ovulatória foram visualizados três estágios bem definidos de desenvolvimento fetal dentro do oviduto: 1) logo após a ovulação (e fecundação), somente o vitelo foi visualizado; 2) o vitelo ocupava 60% e o feto 40% do ovo e 3) o feto estava formado e não havia vitelo. Nos machos, os testículos foram visualizados como uma imagem homogênea e hipoecogênica quando se encontravam em estágio...

The reproduction is part of the animal life cycle allowing the perpetuation and conservation of the species. In snakes, there is a shortage of technical information about the reproductive cycle. The objective of this study was to evaluate the reproductive tract by ultrasonography in captive viviparous snakes of the Boidae family, allowing diagnose of the different reproductive stages. Eleven adult snakes of four species of the Boidae family were sonographically evaluated, Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus and Epicrates cenchria belonging to the Biological Museum's collection of the Instituto Butantan, Sao Paulo Brazil. For the sonographic evaluation, snakes were contained physically with herpetologic hook and then manually for about 15 minutes. The evaluation was done by applying acoustic gel on the skin and positioning the transducer on the right and left side-ventral line, in the medial region of the body in the skull tail sense. Ultrasonography allowed the evaluation of the whole reproductive cycle in snakes. In sonographic evaluations of females were defined the stages of ovarian and ovidutal development. The ovarian follicles during the pre-vitellogenic phase were visualized as homogeneous and anecogenic, in a "bunch of grapes" distribution. In the vitellogenic stage follicles were larger and more echogenic, following each other as a "string of pearls". When there was no copula, the follicles were reabsorbed in the ovary returning to pre-vitellogenic phase. In the post ovulatory phase were seen three well-defined stages of fetal development within the oviduct: 1) just after ovulation (and fertilization), only the vitellus was visualized; 2) occupied 60% of the vitellus fetus and 40% egg and 3) the fetus was formed and no vitellus. In males, the testicles were seen as a homogeneous and hypoechoic image during the reproductive stage...