Uterotubal junction of the bovine (Bos taurus) versus the dromedary camel (Camelus dromedarius): Histology and histomorphometry.

This study aims to conduct a comparative analysis of the uterotubal junction in two distinct mammalian species, the bovine (Bos taurus) and the dromedary camel (Camelus dromedarius), focusing on histological and histomorphometric parameters. Uterotubal junction (UTJ) was dissected from 8 cows and 12 camels with dominant follicles, and processed for H&E staining for histology, and histomorphometry examination. The results showed that the camel uterotubal junction papillae (UTJP) existed only in camels and was completely absent in cattle. Histologically, the cow UTJ appears with a star-shaped lumen, and the mucosa is lined by a simple columnar epithelium with ciliated and non-ciliated cells. Superficial (SG) and deep glands (DG) were abundant in the submucosa. Camel UTJP is a conical structure, it has a pale yellowish colour, 0.5 ± 0.2 cm height, and 0.3 ± 0.1 cm width, and it has a distinct sphincter at the tip towards the uterine lumen. In the camel UTJP, the lumen is wider, and the mucosa showed large multiple folds lined with ciliated and non-ciliated cells in a pseudostratified columnar epithelium. The submucosa showed no mucosal glands. Lumen area, lumen epithelial height, luminal epithelial density, the thickness of the muscular layer, number of folds, fold height, epithelial height, fold area and epithelial perimeter were higher in camel UTJP (p < .001) than cow UTJ, while the total endosalpinx area and glandular epithelial density were lower in camel UTJP (p < .001) than in cow UTJ. In conclusion, this study elucidates potential variations in the uterotubal junction between bovines and dromedary camels, providing valuable insights into their reproductive adaptations. The epithelial lining, absence of glands and the thick layer of tunica muscularis might indicate that camel UTJP could play a mechanical role in selecting spermatozoa and assisting the hatching of blastocysts during their passage into the uterus.