When mouse femoral bone was subcutaneously implanted after the cutting of both ends into the abdominal wall of syngeneic mouse, bone marrow tissue regenerated in the medullary cavity of the bone. We removed the implanted bones at 1-week intervals and evaluated the regenerative process. The medullary cavity underwent necrosis after 1 week. Regeneration of the stromal components appeared in the epiphyses after 2 weeks and progressed with resorption of the necrotic tissue. After 3-4 weeks, myxomatous stroma rich in matrix components formed resulting in enlodgement and proliferation of hematopoietic cells. Marrow graftment was nearly completed after 6 weeks. Immunohistochemical examination showed a large amount of chondroitin sulfate proteoglycan (PG) and large PG in the myxomatous stroma that formed after 3-4 weeks. Biochemical analysis of the glycosaminoglycan chain primarily revealed low-sulfated chondroitin sulfate. Formation of myxomatous stroma rich in chondroitin sulfate PG and large PG seemes to play an important role in the regeneration of hematopoietic tissue.
