VAGINAL ANATOMY OF THE DOMESTIC CAT (FELIS-CATUS) IN RELATION TO COPULATION AND ARTIFICIAL-INSEMINATION

In the course of an investigation of artificial insemination (AI) in t he domestic cat, the site of deposition of the semen during vulval ins emination was questioned. A limited study was carried out to ascertain both the anatomy and distensibility of the vagina and urogenital sinu s, and the location of the cervix in relation to the vulva. In live re strained female cats a 4 mm diameter Teflon probe could not be inserte d more than 20 mm, and elicited a cry similar to the copulatory vocali zation when the resistance was encountered. However, a 1 mm diameter b all-tipped needle was passed to a depth of 40 mm. To confirm these obs ervations, four adult female domestic cats were dissected. The cervix was located approximately 45 mm cranial to the vulva. The urogenital s inus narrowed approximately 17.5 mm from the vulva, preventing the pas sage of a 4 mm probe, and led to a constricted vagina, which permitted the passage of a 1 mm diameter probe to the depth of the cervix. A ra diological investigation of a single anaesthetized cat supported these results. The erect penis of the adult male was measured during sexual arousal in five animals; the mean length and width (+/- SD) was 21.2 +/- 2.2 mm and 5.1 +/- 0.5 mm, respectively. These observations lead u s to conclude that the stimulus for vocalization during natural mating is distention of the posterior vagina, where semen is probably deposi ted. The site of semen deposition is uncertain in several accounts of artificial insemination, as the passage of the insemination device dep ends on its diameter.