Microvascular invasion of rabbit growth plate cartilage and the influence of dexamethasone

The normal morphological features of growth plate angiogenesis were examined in rabbits and compared with changes induced by dexamethasone. Penetration of growth plate cartilage was led by perivascular cells with some contribution by luminal capillary endothelial cells. There was a close relationship between the invasive perivascular cells and the luminal endothelial cells of the capillary tip. Growth plates from rabbits treated with dexamethasone underwent major changes in the pattern of capillary invasion. Most striking was the appearance of numerous narrow and tortuous channels which penetrated the cartilage, in some cases forming complete loops. These channels were filled with debris or red cells but did not contain capillaries. It is suggested that dexamethasone treatment leads to channel formation by disrupting the normal control of capillary invasion.