An electron microscopic examination of articular cartilage of two case
s with multiple epiphyseal dysplasia type II was performed. The cartil
age had a normal cell distribution and no signs of gross degeneration
were found. Chondrocytes showed normal ultrastructural characteristics
without dilation of the rough endoplasmic reticulum. The matrix conta
ined normal banded collagen fibrils, proteoglycans, and aggregated fib
rils.