Figure 3. TUNEL staining of retinal sections. Paraffin sections of eyes from nondiabetic rats (A), nondiabetic rats treated with etanercept (B), diabetic rats (C), and diabetic rats treated with etanercept (D) were assessed by TUNEL. Sections were subsequently counterstained with hematoxylin. Insert shows an overview of a diabetic retina with the ganglion cell layer (above), the inner nuclear layer (middle, light blue) and the outer nuclear layer (below, dark blue). Numbers of positive endothelial cells were counted in each of 12 sections and expressed as percent of total endothelial cells. Treatment with etanercept reduced diabetes-induced endothelial cell apoptosis, as detected by TUNEL staining.