In order to clarify the in vivo localization of aromatase in the ovarian tissues of rat, mouse, guinea pig, golden hamster, cow and human, immunocytochemical investigations using the anti-human placental aromatase II cytochrome P-450 antibody were carried out by the PAP or indirect fluorescent antibody method.
Immunoreactive aromatase was detected on the theca interna, as well as the interstitial gland cells of both immature and mature rodent ovaries and the corpus luteum cell of mature rodent ovaries. The immunoreactivity was also demonstrated on the theca interna cell and corpus luteum cell of cow and human ovaries. Only in large preovulatory follicles of the mature rodent ovary did the granulosa cell react with the antibody of this enzyme, while granulosa cells in all the other follicles were consistently negative in this immunoreaction.
These results might imply that the theca interna cell and interstitial gland cell presumably have a fundamental ability of the aromatization from androgens to estrogens in the mature and immature ovaries.