Figure 1

Histology findings in placebo and steroid-induced ANFH rats. (a) Photomicrographs showing histological findings in placebo- (I-IV) and steroid-treated WKY rats (V-VIII & IX-XII) femoral heads. I-IV: No osteonecrosis, normal osteocytes (arrow), V-VIII: Early stage of osteonecrosis, normal osteocytes (arrow), empty lacunae (arrow head), IX-XII: Late stage of osteonecrosis, empty lacunae (arrow head), complete necrosis of bone marrow (asterisk), H&E staining, I, V, IX ×20; II, VI, X ×40; III, VII, XI ×100; IV, VIII, XII ×200, dotted square chosen to be magnified. (b) Photomicrographs showing apoptosis of osteocytes as a marker of early ANFH. TUNEL staining apoptosis assay counterstained with 0.5% methyl green solution. I-III: Normal femoral head tissues in placebo-treated WKY rats, normal osteocytes (arrow head), normal bone marrow (double asterisk), IV-VI: Early stage of osteonecrosis in steroid-treated WKY rats, TUNEL positive osteocytes (arrow), empty lacunae (dotted arrow), normal osteocytes (arrow head), normal bone marrow (double asterisk). VII-IX: Late stage of osteonecrosis in steroid-treated WKY rats, TUNEL positive osteocytes (arrow), empty lacunae (dotted arrow), complete necrotic bone marrow (asterisk), I, IV, VII ×40; II, V, VIII ×100; III, VI, IX ×200, dotted square chosen to be magnified.