Immunohistochemical localization of the progesterone and oestrogen alpha receptors in the uterine horns of the African giant rat (Cricetomys gambianus).

The present study investigated the immunolocalization of the progesterone and oestrogen alpha receptors in the uterine horns of the African giant rat during the oestrous cycle. The progesterone and oestrogen alpha receptors were demonstrated in various cellular constituents of the endometrium, myometrium and perimetrium. The intensity of progesterone and oestrogen alpha receptor immunostaining in the endometrial and myometrial layers of the uterine horns varied during the oestrous cycle. The intensity of oestrogen alpha receptor immunoreactivity in the luminal epithelium was high during pro-oestrus, oestrus and dioestrus. Progesterone and oestrogen alpha receptor immunoreactivity in the endometrial epithelia was absent during metoestrus. Moderate to strong immunostaining for the progesterone and oestrogen alpha receptors was demonstrated in the myometrial smooth muscle cells during pro-oestrus, oestrus and dioestrus. The intensity of progesterone and oestrogen alpha receptor immunostaining in the myometrial smooth muscle cells was low during metoestrus. Stromal cells in the perimetrium consistently expressed progesterone and oestrogen alpha receptor immunoreactivity throughout the oestrous cycle. The findings of the study indicate that in the giant rat the immunolocalization of the progesterone and oestrogen alpha receptors, in endometrial and myometrial regions of the uterine horns, varies during the oestrous cycle.