Figure 1.

A: Endometriosis samples immunostained for EPO. There was positive staining in intact eosinophils (dark, red-brown deposits) and on free eosinophil granules in the loose connective tissue . B: Staining was especially intense in band-like deposits at the edges of lesions. C: Intact eosinophils with EPO activity were often detected within and near small blood vessels. Eosinophils and EPO were not detected in or near the glandular portions of endometriosis (D), but intact eosinophils were occasionally observed in the myometrium (E). A strikingly fibrillar distribution of EPO was also frequently observed (D, upper right corner). G: Hemosiderin-laden macrophages could be seen in proximity to eosinophils but had different tinctorial properties. Original magnifications: D and G, ×400; A, C, E, and F, ×200; B, ×100. Hematoxylin counterstain and DAB chromogen.