Testicular maintenance and masculinized development of the vagina of the androgen-insensitive male rat pseudohermaphrodite.

The vaginae of about one-third of androgen-insensitive male rat pseudohermaphrodites never open nor can they be opened by the administration of estrogen, progesterone or andorgens. The vaginae of the remaining pseudohermaphrodites open significantly later than normal females, and, once open, require the presence of the testes or exogenous estrogen to maintain their patency. These defects in the vaginal development of the pseudohermaphrodite may be due to some perinatal masculinization of the perineum, unlike most of the phenotypically female development exhibited by this animal.