The urethra anatomical features and its blood supply in the Baikal seal

The aim of research is to study the anatomical features of the urethra and its blood supply in the Baikal seal. The objects of the study were the bladder, urethra, internal pudendal arteries of male and female Baikal seals at the age from 7 months to 7 years. The urethra of the male Baikal seal is a hollow muscular organ that consists of two parts: the urinary tract and the urogenital. The urinary tract begins with an opening from the neck of the bladder, and the urogenital canal begins from the entry point of the vas deferens, which serves not only to excrete urine, but also to carry sperm. The urethra of a female Baikal seal is hidden in the pelvic cavity. It originates from the bladder neck, lies under the vagina in loose connective tissue and behind the pubic bones of the pelvis at the level of the 1st sacral – 1-2nd caudal vertebrae and flows into the urogenital vestibule. The vestibule, its ventral wall, serves to drain urine. The blood supply to the urethra of the male and female of the Baikal seal is carried out by the internal pudendal artery. The artery runs along the vertebrae in the caudal direction, extends to the urethra and enters it. Intraorganic blood supply to the muscular layer of the urethra is characterized by the presence of a large number of blood vessels, in particular venous, the shape and diameter of the lumen of which in the collapsed state are different. The vessels of the arterial bed are arranged in pairs, the thickness of their walls is on average 1/2–1/3 of the diameter of the lumen. These results will contribute to the comparative species morphology of aquatic mammals.