The histological features of the iliac cartilage growth plates in patients with Risser grade 2. a) A girl with sacrum tumor (age: 13.7y, 4 month postmenarche Risser 2). b) A girl with IS (age: 14.3y, 3 month postmenarche, Risser 2). A thinner hypertrophic zone, smaller area of cell-nest, fewer cells in the cell-nest in the hypertrophic zone, and fewer chondrocytes in the proliferative zone were found in both patients, indicating less growth activity. No significant differences were identified between the IS (b) and control (a) patients with Risser grade 2. HE, 200×.