Trauma as a stimulus to marrow regeneration in the osteosclerotic mouse

Hemopoietic regeneration was studied in the tibia of mice rendered osteosclerotic by estrone injections. Trauma induced by fracture and periosteal damage was followed by a local hemopoietic response in both normal and osteosclerotic mice. Endosteal damage induced by drilling an artificial cavity in the osteosclerotic tibia was not followed by local hemopoietic regeneration, whereas in normal tibias similarly treated incomplete hemopoietic regeneration was observed. These studies indicate that trauma induced by fracture and periosteal damage is followed by a fairly uniform local hemopoietic regenerative response regardless of whether or not marrow is present in the traumatized bone. Creation of a simulated marrow cavity by drilling through osteosclerotic bone is an insufficient stimulus for hemopoietic regeneration in the mouse. New bone tissue was found to occupy the drilled shaft. This suggests that failure to regenerate hemopoietic tissue may be a consequence of insufficient bone resorption. A differential effect of trauma on endosteal and periosteal tissue is therefore postulated.