An examination of the fine structure of proximal tibia-epiphyseal cartilage (3-5 weeks-old rabbit) has ravealed the following information.
1) Chondrocytes of epiphyseal cartilage contain numerous cytoplasmic processes, and in their cytoplasm many vacuoles. The so called cartilage lacuna, like a halo, which gradually proceeds to the cartilageons matrix is seen around the cell to a certain extent.
2) The matrix appears to be irregularly intricated, possessing a felt-like structure, with fibre and then small fibres appear, without demonstrable periodicity, on the longitudinal septa.
It is assumed that these fibres develop from the granules in the cartilage lacuna, in the cytoplasmic vacuoles.
3) Chondrocytes involve changes in cytoplasmic hydration rather than changes in the organelles. After maximum hydration, chondrocytes undergo death and degeneration.
4) Calcification initiates on the longitudinal matrix with relative electron-dense granules, gradually, forming itself into islets and granular specks. As they increase in number and volume, they fuse with each others to complete the formation of calcified cartilage.
