The Vestibule (Figures 14.5-14.8)

The vestibule is the part of the female reproductive tract that extends from the labia of the vulva to the urethral orifice; cranially the tract continues as the vagina. When visible the hymen is a transverse membrane just cranial to the urethral orifice.

Figure 14.5 Dorsal view the vestibule of the mare.

Figure 14.6 Dorsal view the vestibule of the cow.

14.7.1 Species variations

Mare (Figure 14.5): The external urethral orifice is easily located. The glans clitoridis is much larger than in the other domestic mammals; it is a conspicuous, smooth, rounded body, about 1.5 cm in diameter and visible during micturition. It is located within the fossa clitoridis. Swabs for the diagnosis of the notifiable disease contagious equine metritis are taken from the fossa clitoridis.

The hymen is not usually visible. Two rows of vestibular glands are visible.

Cow (Figure 14.6): The external urethral orifice is slit-like and is located cranioven- tral to the large suburethral diverticulum in which the actual urethral opening is found. Gartner’s ducts (remnants of the mesonephric ducts) open either side of the urethral orifice. The fossa and glans clitoridis are small and not easily located.

The vestibular glands open along a midline ventral groove. In addition, there is a sin­gle compound gland on each side termed a major vestibular gland.

Sow (Figure 14.7): The external urethral orifice is bounded laterally by thick folds. Gartner's glands may be present. The hymen is rarely identifiable. Two rows of vestibu­lar glands are present.

Bitch (Figure 14.8): The external urethral orifice opens on a midline ridge, the ure­thral tubercle, and has a fossa on either side. The glans clitoridis is small and lies within a deep fossa. The fossa clitoridis may be mistaken for the external urethral orifice when catheterising the urethra. The vestibular glands open in two lines ventrally.

Figure 14.7 Dorsal view the vestibule of the sow.

Figure 14.8 Dorsal view the vestibule of the bitch.

14.8