Fig. 2

Immunohistochemical grading of the expression of IDO in endometrium. The grading was performed based on staining intensity, as described in the materials and methods, grade 1: no or weak staining and scarcely positive, IDO was localized in the stromal compartment (a); grade 2: moderately stained and focally positive, IDO was localized in surface epithelial cells (b); grade 3: strongly stained and diffusely positive, IDO was localized in glandular epithelial cells (c); scale bars = 100 µm, with insets = 10 µm