The Vagina, Vestibule, and Vulva
The vagina is about 7 to 12 cm in length. It is unremarkable, and the vestibule is relatively long. The vestibule has openings for the minor vestibular glands and has solitary lymph nodes.
The conical vulva slopes so that it faces rather obliquely upward (Fig. 35.2A/7); it is sometimes so upturned that the cleft is inaccessible to the boar. Gilts with an infantile vulva are common, and the defect hints at poor development of the reproductive organs and greater risk of infertility. The clitoris is normally barely visible (Fig. 35.4/17). Clitoral enlargement is common and is associated with intersexuality (female pseudohermaphroditism).The uterine artery, the principal supply to the uterus, is supplemented by branches of the ovarian and vaginal arteries (Fig. 35.5/2 and 7). The ovarian vein, which drains most of the uterus in addition to the ovary, forms a plexus around the uterine and ovarian arteries that facilitates the transfer of luteolytic prostaglandins.
The examination of the reproductive tract is done to determine the reproductive health of the animals. Many times the reproductive tract is collected in the slaughterhouse to examine it for gross and histologic abnormalities to determine causes of reproductive failure. Therefore, the knowledge of the anatomy of the reproductive organs is of vital importance.
FIG. 35.2 (A), The reproductive organs of the sow in situ. (The presence of the intestines in the intact animal causes the ovaries and uterine horns to lie more dorsally than shown here.) 1, Descending colon;
2, ovary; 3, uterine horns; 4, broad ligament; 5, bladder; 5', urethra; 6, suburethral diverticulum; 7, vulva; 8, rectum; 9, cervix. (B) Transrectal ultrasonographic image and (C) transabdominal ultrasonographic image and schematic of 30-day gravid porcine uteruses. (Scales in centimeters.) 10, Allantoic fluid-filled spaces;
11 and (a), embryo.