Fine structure of rabbit articular chondrocytes in tissue culture during logarithmic and confluent stages of growth.

Ultrastructural changes in cultured articular cartilage chondrocytes from rabbit, during two growth phases were examined by transmission and scanning electron microscopy. Cells in logarithmic growth are characterized by an abundance of intracellular lipoid bodies, little development of rough endoplasmic reticulum (RER), and few cytoplasmic microfilaments. As the cells reach confluency there is a concomitant development of RER, organization and abundance of microfilaments, loss of lipoid bodies, and increase in the number of mitochondria. The fine structure of cultured chondrocytes is very similar to that of rabbit cartilage cells in situ, in that numerous lipoid bodies and microfilaments are prominent features in both cases.