Morphophysiology of the Female Reproductive System

The organs of the vizcacha’s reproductive system are like those of other eutherian mammals. However, some organs exhibit species-specific morphological characteristics. The ovaries of the vizcacha are flat and have multiple folds, which increase their surface area. This unique feature enables the polyovulation of 200–800 oocytes per estrus, the highest ovulatory rate observed among mammals. The morphology of the oviducts and uterine horns is comparable to that of other mammals. However, the caudal segments of the uterine horns have significantly thicker walls, tunics, and glandular and vascular areas as compared to the cranial and middle segments. These anatomical differences have not been reported in other mammals. Studies on female fetuses have shown that the uterine horns already exhibit differences along the craniocaudal direction during prenatal life, which have been associated with spontaneous embryonic death in the cranial and middle implantation sites. Additionally, the vizcacha has a non-muscular cervix and a well-developed paraurethral gland (female prostate) found in all analyzed specimens. The expression of glycoconjugates and glycosidic residues in the organs of the female reproductive system varies according to the reproductive physiological state.