| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1990: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Research Abstract |
[Purpose] Since the process of osteoclast formation and its relation to the osteoblast in the periosteum of the embryonic limb buds were not well known, the following study was performed. [Methods] 1) The femora of the embryonic 15-day-old C_3H mice together with the periosteum were processed for electron microscopy, in order to observe the osteoclasts and their precursors. 2) Twenty-five units of parathyroid hormone was injected into the omnioic fluid of 14-day-pregnant C_3H mice and 24 hours later the femora were dissected, reacted with tartrate-resistant acid phosphatase (TRAP) and then processed for electron microscopy, in order to observe the osteoclasts and their precursors. 3) The femora of embryonic 17-day-old C_3H mice were dissected and co-cultured with the osteoblastic cell line named KUSA. [Results] 1) Osteoclasts and osteoblasts were rarely very closely contact each other, while the preosteoclasts and osteoblasts were not closely contact each other at all. Therefore, it is not clear whether the osteoblasts really play an important role in differentiation of the preosteoclasts or not. 2) Using TRAP as tracer, the osteoclast precursors were pursued. The youngest precursor was of a high nucleus/cytopasm ratio, having clear nucleus, and its cytplasm contained a relatively few mitochondria as well as TRAP-positive lysosomes. The precursors were not similar to any of hematopoietic stem cells, monoblasts, promonoblasts, monocytes, or macrophages, but to the undifferentiated perivascular cells ultrastructurally. 4) An experiment using co-culture with KUSA has not been so far successful. 5) We reported the above-mentioned results at a couple of Medical Meetings and have sent our manuscript on this study to the Journal "International Orthopaedics".
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