Proliferation of bone marrow and thymus cells and increased osteoclasia after antigenic challenge in rats.

Injection of a single dose of an antigenic substance (sheep red blood corpuscles) in young rats results in a significant rise in the number of mitoses in bone marrow (and in thymus) and in addition a significant rise in the number of osteoclasts in the metaphyses of the ribs. This increased osteoclasia appears 1 day after the peak values of the bone marrow and thymus mitoses. This and earlier investigations make it probable that there is a causal relationship between bone marrow stimulation and increased osteoclasia.