AGE-RELATED-CHANGES AND OSTEOCHONDROSIS IN SWINE ARTICULAR AND EPIPHYSEAL CARTILAGE - LIGHT AND ELECTRON-MICROSCOPY

Abstract

Age related changes and osteochondrosis in swine were studied using light microscopy and EM in articular cartilage and light microscopy in epiphyseal cartilage of swine from 3 days to 30 wk of age. Thickness, cellularity and vascularity of the epiphyseal and articular cartilage, decreased as the swine aged. Osteochondrotic changes included formation of plugs of cartilage indicating localized failure of ossification and separation and space formation in epiphyseal cartilage. Eosinophilic streaks and space formation in epiphyseal cartilage was observed in relation to epiphyseal separation. EM showed a continuous fibrillar layer on the surface of the cartilage corresponding to the lamina splendens of light microscopy. This layer increased in thickness and showed accumulation of amorphous material between the fibrils with aging. In the matrix orientation and distribution of collagen fibers changed with growth. Thicker fibers with clear sub-banding were more common in older age groups. Necrotic cells, glycogen containing bodies and cellular debris were noticed in the matrix of normal cartilage in old animals. Chondrocytes in the younger cartilage showed accumulation of organelles responsible for protein synthesis; while Golgi bodies, vesicles, lysosomes, well developed foot processes and other inclusions were noticed in older cartilage. Cartilage erosions had a clumped and disrupted lamina splendens on the surface and electron lucent patches in the ground substance of the matrix and chondrocyte cytoplasm.