Figure 2.

Expression pattern of angiotensin-converting enzyme 2 (ACE2) protein in periovulatory follicles. Dominant follicles were retrieved from the ovaries of women undergoing laparoscopic tubal sterilization before the luteinizing hormone surge or at various times after recombinant human chorionic gonadotropin administration. The paraffin-embedded sections of dominant follicles obtained at various time points (A, preovulatory phase, n = 2; B, early ovulatory phase, n = 4; C and D, late ovulatory phase, n = 4; E, late ovulatory phase, n = 1) were subjected to immunohistochemical analyses to detect ACE2 protein. The sections in C and D are from different patients obtained from the late ovulatory period. F is an antrum region of the postovulatory follicle shown in panel E. Pink/red staining indicates positive signals for ACE2. All sections were lightly stained with hematoxylin (blue staining) for nuclear counterstaining. Arrows point to granulosa and theca cells where intense staining for ACE2 was detected. Wavy arrows point to ACE2 staining in the stroma layer. GC = granulosa cells; GLC = granulosa lutein cells; RBC = red blood cells; TC = theca cells; TLC = theca lutein cells; Scale bar in A = 100 μm.