How Does Oocyte Uptake Occur? A Macroscopic Study of the Ovarian and Oviductal Modifications for Egg Capture in the Coral-Snake Micrurus corallinus

Anatomy of the female reproductive tract organs of the brown anole (Anolis sagrei)

Female reproduction in squamate reptiles (lizards and snakes) is highly diverse and mode of reproduction, clutch size, and reproductive tract morphology all vary widely across this group of ~11,000 species. Recently, CRISPR genome editing techniques that require manipulation of the female reproductive anatomy have been developed in this group, making a more complete understanding of this anatomy essential. We describe the adult female reproductive anatomy of the model reptile the brown anole (Anolis sagrei). We show that the brown anole female reproductive tract has three distinct anterior-to-posterior regions, the infundibulum, the glandular uterus, and the nonglandular uterus. The infundibulum has a highly ciliated epithelial lip, a region where the epithelium is inverted so that cilia are present on the inside and outside of the tube. The glandular uterus has epithelial ducts that are patent with a lumen as well as acinar structures with a lumen. The nonglandular uterus has a heterogeneous morphology from anterior to posterior, with a highly folded, ciliated epithelium transitioning to a stratified squamous epithelium. This transition is accompanied by a loss of keratin-8 expression and together, these changes are similar to the morphological and gene expression changes that occur in the mammalian cervix. We recommend that description of the nonglandular uterus include the regional sub-specification of a "cervix" and "vagina" as this terminology change more accurately describes the morphology. Our data extend histological studies of reproductive organ morphology in reptiles and expand our understanding of the variation in reproductive system anatomy across squamates and vertebrates.

Monitoring of the Reproductive Cycle in Captive-Bred Female Boa constrictor: Preliminary Ultrasound Observations

Simple Summary

In recent years, reptiles have become increasingly popular pets. The growing interest in snakes has led to an increase in captive-bred ophidians, and the Boa constrictor is one of the most common reptiles bred in captivity. These snakes can be found in tropical South America, as well as some islands in the Caribbean. With the exception of one subspecies, the Boa constrictor is now included in Appendix II of the Convention on International Trade of Endangered Species (C.I.T.E.S.). In order to achieve the proper management of boas in captivity, it is essential to have in-depth knowledge on the reproduction of this species and to identify minimally invasive methods for a correct monitoring of the reproductive cycle and gestation, guaranteeing the animal’s welfare. Currently, ultrasonography is the most common technique used in veterinary medicine for evaluating reproductive activity in both mammals and reptiles. In this regard, knowledge of the Boa constrictor is rather scarce. A group of captive-bred female boa constrictors were monitored by ultrasound over an entire breeding season. Results suggest that this technique allows an accurate monitoring of the captive female boas’ reproductive cycle, as well as a precise control of the embryos’ development and viability.

Abstract

The Boa constrictor is one of the most common reptiles bred in captivity. To achieve a successful breeding season, thorough knowledge of the females’ reproductive activity is necessary. In this regard, information on the Boa constrictor is still rather scarce. The aim of the present study was to monitor the ovarian activity and the embryonic development of boas by ultrasound. We performed brief scans on thirty non-anaesthetized snakes using a portable ultrasound system and a 7.5–10 MHz linear array transducer (Esaote MyLab™ Classic). Ultrasound features, dimensions, and echogenicity of the preovulatory and postovulatory follicles were determined. As gestation progresses, the postovulatory follicle size increases, and the embryonic silhouette becomes increasingly recognizable. During the second month after ovulation, by using color Doppler, early embryos’ heart activity could be evaluated. It is possible to highlight vascular connections between the mother and the membrane covering the embryonic structures. Ultrasound also allows one to identify follicular regression or slugs (nonfertilized eggs) early. The present study suggests that ultrasound could be an excellent noninvasive technique to evaluate the reproductive activity of Boa constrictor, allowing us to precisely identify the correct time for mating, monitor embryo development and viability, and allow the early diagnosis of follicular regression.