The immunocytochemical localization of angiotensinogen in the rat ovary.

The present study examined the presence and cellular distribution of angiotensinogen, the precursor to the angiotensin peptides, in the ovary of the normal cycling rat by immunocytochemistry. Angiotensinogen staining was present in the granulosa cells of maturing follicles and to a lesser extent in those undergoing atresia. Staining was not seen in the granulosa cells of primordial or early primary follicles. In maturing follicles intense staining for angiotensinogen was confined to the antral cell layers, cells of the cumulus oophorus and in the follicular fluid. Strong immunostaining was also seen in the germinal epithelium covering the ovary. Lighter angiotensinogen staining was observed in some parts of the cortical and medullary stroma and occasionally in corpora lutea. No variation in the intensity or pattern of angiotensinogen staining was observed throughout the estrous cycle. Comparison of the distribution of angiotensinogen with the previously described localization of renin, AII, angiotensin converting enzyme and AII receptors, suggests that there are a number of intra-ovarian sites at which AII could be produced.