Acute Ultrastructural Alterations in Irradiated Proliferative Chondrocytes of Rat Growth Cartilage

Abstract

Ultrastructural changes in proliferative chondrocytes of rats exposed to 7 krads of were studied X-rays 2, 4, 8, and 10 days after irradiation. The lesion is characterized by disorganization of the epiphyseal plate with marked involutive changes of the cells. Two days after irradiation, there is a slight dilation of the endoplasmic reticulum. As from the fourth post irradiation day on, a marked saccular and lacunar dilation of these structures could be seen. Vacuolar structures related with the Golgi complex and lipid droplets could be noted 4, 8, and 10 days after irradiation. Lysosomes, which normally are not seen in proliferative chondrocytes, were also noted during this study. Cytoplasmic fragmentation and an increasing number of calcifying globules could be observed in the 8- and 10-day groups. Nuclear fragmentation, lobulation, and the presence of binucleated viable cells were other signs of cell division alteration produced by radiation. The decrease of proteoglycan granules and collagen fibrils in association with the endoplasmic reticulum and Golgi changes points to a probable damage of the synthetic and secretory activities of chondrocytes.