Morphologic studies of rectovaginal constriction in Jersey cattle.

Tissues associated with rectovaginal constriction (RVC) in Jersey cattle were studied. Nine affected and tow control Jersey cows were subjected to clinical, gross, and microscopic examinations. The anus, perineum, vestibule, vagina, and uterus were examined histologically. Sections of musculature containing anorectal and vestibular fibrous tissue bands were examined by scanning and transmission electron microscopy. Nonelastic fibrous tissue bands located at the anorectal junction and within the vestibular muscularis were common to the RVC cows. Light and scanning electron microscopic examination revealed variable amounts of fibrosis affecting the external anal sphincter muscle. Both tissue bands were composed of well-vascularized, irregular connective tissue containing randomly distributed myofibers and adipose tissue No abnormalities in ultrastructure of the tissue bands were seen by transmission electron microscopy. The collagen had normal periodicity and the striated muscle had normal cross banding.