Fig. 2.

Optical microscopy shows (A) extensive apoptosis in femoral head osteocytes from a patient with steroid-induced osteonecrosis, (B) absence of apoptotic osteocytes in a patient with idiopathic osteonecrosis and (C) moderate apoptotic osteocytes in a patient with alcohol-induced osteonecrosis. The apoptotic osteocytes were stained brown with diaminobenzidine substrates, whereas non-apoptotic osteocytes are stained blue with hematoxylin (× 400).