Abstract
1. The mesenchymal tissue prospective to form the parietal bone of rabbit was transplanted into the anterior eye chamber of adult rabbits. Though bone formation was found in the transplanted mesenchym resected from a 16 day-old foetus and the older, it was not proved in the transplanted mesenchym originated from a 15 day-old foetus and the less. From this experiment, it is evident that the cranial mesenchym of rabbit foetus under 17 days old is not “determined” to osteogenesis.
2. The mesenchym of rabbit foetus under 16 days old, in which osteogenesis was “undetermined” yet, exhibited osteogenetic activity only when the brain tissue co-existed with it in the anterior eye chamber. Then it is concluded that the parietal bone is “induced” by the brain tissue.
3. It was proved that the brain tissue had an activity of bone induction in neonatal rabbits as well as in foeti, but the activity decreased rapidly one month after birth.
4. The simultaneous completion of blood-brain barrier with disappearance of bone induction activity in the brain and its possible role were discussed.
