Quantitative analysis of rough endoplasmic reticulum in chondrocytes of articular and tracheal cartilage of rabbits following the systemic administration of hydrocortisone

Abstract

The rough endoplasmic reticulum (RER) in chondrocytes was analysed stereologically in articular cartilage of knee joints and in tracheal cartilage of rabbits injected intramuscularly with 5 mg/kg hydrocortisone daily for 4 wk. In articular cartilage, RER area per unit cytoplasmic volume decreased in chondrocytes in all (superficial, middle and deep) zones, although the volume of glycogen deposits per unit cytoplasmic volume increased in the middle and deep zones. RER area per chondrocyte also decreased in the 3 zones without changes in average chondrocyte volume in the superficial and deep zones. Furthermore, the volume of glycogen deposits per chondrocyte did not alter in the 3 zones. These indicate a reduction of RER area in articular chondrocytes after hydrocortisone administration and suggest a decrease in the protein-synthesising capacity of these cells. In tracheal cartilage in which 2 zones were identifiable, RER area per unit cytoplasmic volume decreased in chondrocytes in both the superficial and main zones without changes in the volume of glycogen deposits per unit cytoplasmic volume. In addition, RER area per chondrocyte decreased in the main zone. The results suggest that the decrease in RER area in chondrocytes after corticosteroid administration is not specific to articular cartilage but is common to cartilage in various organs.