The response of bone marrow cells, thymocytes and osteoclasts to hydrocortisone.

Hydrocortisone injections in young rats caused an increase in the proliferative response of bone marrow cells but a disintegration of thymus gland, the cells of which probably disappeared from thymus. Earlier investigations have shown that different kinds of trauma and antigen result in an increase in the mitotic rate of bone marrow and thymus cells and at the same time an increase in the number of osteoclasts. After steroids, however, no increase of osteoclasts occurred, probably because monocytes which develop into osteoclasts and macrophages are inhibited by hydrocortisone. The effect on serum calcium was minimal.