Bone particles from toothless (tl/tl) osteopetrotic rats not cured by bone marrow transplantation are resorbed in normal littermates.

We examined the possibility that the failure of toothless (osteopetrotic) rats to be cured by bone marrow transplantation from a normal littermate is due to the production of poorly resorbable bone. Mineralized bone particles from mutants (tl/tl) and normal littermates were implanted subcutaneously in normal rats of this stock. The removal of bone and recruitment of multinucleated giant cells were evaluated by histomorphometry. No differences were found between mutant and normal bone from this stock or from two other osteopetrotic rat stocks, incisors-absent and osteopetrosis, known to be cured by bone marrow transplantation. Subject to the limitations of this method, these data suggest that the failure of tl/tl rats to be cured by bone marrow transplants from normal littermates is not due to the production of unresorbable bone or a bone matrix deficient in its ability to recruit multinucleated giant cells and presumably osteoclasts.