Carcinoma of the Vaginal Wall in the Rabbit*

The characteristic distribution of uterine cancer in man with a high incidence in the cervix and a low frequency in the fundus does not obtain in the rabbit. Carcinoma of the uterine fundus is by far the most common of all neoplasms in the rabbit (1) whereas cervical cancer has not been observed in our laboratory nor has its occurrence been reported in the literature. The absence of a squamocolumnar junction in the rabbit 's cervix suggests an anatomical basis for the species variation. Unlike the situation in man where columnar and squamous epithelium meet in the region of the external os, the columnar epithelium of the rabbit 's fundus continues uninterruptedly over the cervix and down the vaginal wall to a junction with squamous epithelium at about the level of the urethral meatus. The object of the present paper is to report three cases of epidermoid cancer at this site. The occurrence of cancer at the squamocolumnar junction in both man and the rabbit despite its different location in the two species emphasizes the significance of the junction as a predisposing factor in carcinogenesis.