Structure of Physis–

Extending from Epiphysis to Diaphyseal ends of the Growth Plate/Physis                4 Zones:

1. ZONE OF RESTING CARTILAGE/GERMINAL ZONE: –adjacent to epiphysis
   – cells small, irregularly arranged
2. ZONE OF PROLIFERATING CHONDROCYTES: -cells larger
   -undergo rapid mitosis
   -arranged in parallel columns→ separated by bars of intercellular matrix
3. ZONE OF HYPERTROPHY: -cells gradually mature, grow larger & accumulate Glycogen & Alkaline Phosphatase; Type X collagen-a distinguishing feature of hypertrophic chondrocyte.
4. ZONE OF PROVISIONAL CALCIFICATION: -thinner
   -abuts directly on the bone of diaphysis
   -matrix become calcified
   -continuous transformation of the epiphyseal cartilage to bone.

Zone/Groove of Ranvier:   –a triangular microscopic structure at the periphery of the physis,
-containing fibroblasts, chondroblasts, and osteoblasts
-responsible for peripheral growth of physis.

Perichondral ring of LaCroix:  -a fibrous str overlying the Zone of Ranvier
-connects metaphyseal periosteum to cartilaginous epiphysis
-important mechanical function→ stabilizes the epiphysis to the metaphysis.