Histology of the Internal Reproductive Organs of the Female Oryx (Oryx leucoryx)

Abstract

The Arabian oryx has been listed as a vulnerable species. Its conservation and propagation are aided with the deep knowledge of the anatomy of the reproductive system. Nowadays, there is a description of the gross anatomy of this system, but not on its microanatomy. In order to describe the histological features of the internal reproductive organs of the Oryx leucoryx, the ovaries, uterine tubes, uterus, and vagina were collected at necropsy of an adult (6‐year‐old) female oryx and immersed in 4% buffer formalin. Representative samples from each organ were taken and processed for routine histology. Tissue sections of 5 μm were mounted, stained with H&E, and evaluated under light microscope. The ovaries (16 mm in length) are covered by a simple cuboidal epithelium, the germinal epithelium. Beneath this epithelium is a layer of dense connective tissue, the tunica albuginea. The tunica covers the cortex, which in turn encloses the medulla. The cortical stroma merges indistinctly with the medulla and embeds few follicles at several stages of development and a corpus luteum. A large number of corpus albicans are located in the cortex. A rich bed of blood vessels of several sizes are present in the medulla, especially at the hilum zone. The uterine tubes (80 mm in length) are muscular ducts, which are comprised of a serosa, muscularis, lamina propria, and epithelium. The muscularis is mainly constituted of circular smooth muscle covered by a thin layer of longitudinal fibers. The mucosa has longitudinal folds and is made of a pseudostratified epithelium with ciliated and non‐ciliated cells. The bicornuate uterus lacks a body and each horn opens in a cervix. The uterine horns (140 mm in length) have several layers, from outer to inner: a serosa, muscularis, lamina propria, and mucosa. The muscularis contains two layers of smooth muscle, an inner circular layer and an outer longitudinal one. A rich vascular stratum separates these layers. The mucosa is lined by a pseudostratified epithelium. Simple coiled glands are present in the lamina propria. Nonglandular regions with highly cellular elevations are present in the mucosa, the caruncles. The mucosa of each cervix contains four dense rings lined by longitudinal folds made of a stratified squamous epithelium. Numerous glands are located in the lamina propria and contain simple columnar epithelium. The vaginal wall was made of a serosa (cranial region) or adventitia (caudal region), muscularis, lamina propria and mucosa. The inner layer of the muscularis consisted of circular smooth muscle fibers enclosed by longitudinal fibers. The mucosa is made of stratified squamous epithelium. In summary, the histology of the internal reproductive organs of the oryx is similar to that of other mammalian species, especially ruminants.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.