Rough endoplasmic reticulum and fine intracytoplasmic filaments in articular cartilage chondrocytes of young XXXX ; a stereological morphometric study using transmission electron microscopy.

@entity1893 @entity95
Articular cartilage of eight young NZW @entity95 was investigated by electron microscopy. A simple and rapid stereological method was designed for quantifying the synthetic activity of the chondrocytes in the different zones of uncalcified articular cartilage by measuring the amount of @entity1893 ( @entity1893 ) on electron micrographs. The surface area of @entity1893 per unit volume of chondrocyte cytoplasm, of cartilage, and per chondrocyte, were determined. In addition the volume density, and mean diameter, of @entity1893 cisternae were computed. The surface area of @entity1893 was least in the superficial zone (402 micron 2) and largest in the deep zone (879 micron 2) chondrocytes. The @entity1893 surface area per unit volume of tissue was, however, significantly (P less than 0.05) greater in the superficial zone (12.8 X 10(-2) micron2/micron3) than in the deep zone (8.5 X 10(-2) micron2/micron3) of the articular cartilage. Percentages of chondrocytes displaying masses of intracytoplasmic fine filaments were also registered. 8.5% of the chondrocytes in the superficial, 48.8% in the middle, and 53.5% in the deep zone contained intracytoplasmic fine filaments. Chondrocytes containing filaments are probably degenerating cells. They contained diminished amounts of @entity1893 . The altered nutritional status in the deeper zones of the cartilage might have caused these changes in the cells. The formation of the calcified zone of the cartilage in the young @entity95 , contributing to the cessation of the nutritional supply of chondrocytes from the subchondral bone marrow spaces, may have affected the process. Since the proportion of @entity1893 can be regarded as indicating the synthetic activity, and that of filaments as indicating the degree of degeneration, these parameters can be used in the evaluation of the functional status of the uncalcified articular cartilage chondrocytes.
