Histology of the internal reproductive organs of the female Arabian oryx (Oryx leucoryx).

The Arabian oryx (Oryx leucoryx) is an antelope that is considered a "vulnerable" species. Lack of knowledge on the structure of its reproductive organs hinders the development of strategies to improve its reproduction. There is only one report on the gross anatomy of the female reproductive organs. With the aim of describing their microanatomy, the ovaries, uterine tubes, uterus, and vagina were collected at necropsy of an adult female oryx. Samples from each organ were analyzed with H&E staining and light microscopy. The squamous to cuboidal germinal epithelium covers the dense tunica albuginea of the ovaries, which encloses the cortex. This merges smoothly with the medulla. The cortex embeds follicles at several stages of development. A rich bed of blood vessels is present in the medulla, especially at the hilum. The uterine tubes are comprised of a serosa, muscularis, and mucosa. The muscularis is constituted of circular smooth muscle covered by a thin layer of longitudinal fibers. The mucosa has longitudinal folds lined by a pseudostratified epithelium with ciliated cells. The uterine horns are constituted of a serosa, muscularis, and mucosa. The muscularis contains an inner circular layer of smooth muscle and an outer longitudinal one. Simple coiled glands are present at the base of the mucosa. From this, highly cellular projections (caruncles) are present, lined by a by a simple columnar epithelium. The cervix contains four dense rings, and its mucosa is lined by longitudinal folds of a simple columnar epithelium, with ciliated cells. Numerous glands are located in the lamina propria and contain simple cuboidal to columnar epithelium. The vaginal wall was made of a serosa, muscularis, and mucosa. The mucosa is made of stratified squamous epithelium non-keratinized. In summary, the histology of the internal reproductive organs of the oryx is like the one of other ruminants.