Which zone contains chondrocytes that rapidly divide to push cartilage into lengthening bone?

Which zone contains chondrocytes that rapidly divide to push cartilage into lengthening bone?

• A. Resting (reserve) zone
• B. Proliferation zone
• C. Hypertrophy zone
• D. Calcification zone

Answer: (B)

The zone that drives lengthening of the bone is the zone of proliferation. Here, chondrocytes divide rapidly and align into columns, creating new cartilage that pushes the existing cartilage outward toward the metaphysis, which lengthens the bone. In contrast, the resting zone contains quiet, inactive cells; the hypertrophy zone has enlarging chondrocytes; and the calcification zone involves calcified matrix and cell death before bone replacement.

The zone that drives lengthening of the bone is the zone of proliferation. Here, chondrocytes divide rapidly and align into columns, creating new cartilage that pushes the existing cartilage outward toward the metaphysis, which lengthens the bone. In contrast, the resting zone contains quiet, inactive cells; the hypertrophy zone has enlarging chondrocytes; and the calcification zone involves calcified matrix and cell death before bone replacement.