Quarterly Journal of Microscopical Science, Vol s3-88, 367-382, Copyright © 1947 by Company of Biologists

Localization of Alkaline Phosphatase in Mammalian Bones

¹ Department of Physiology, Middlesex Hospital Medical School

1. Adult mammalian bones may be decalcified in sodium citrate-HCl buffer at pH 4.5. The addition of Zn (10^-4 M) prevents irreversible destruction of alkaline phosphatase which is, however, partially inactivated.

2. The phosphatase is subsequently reactivated by placing the tissues in 1 per cent, sodium barbitone +0.075 per cent, glycine at 37° C. for 2-3 hours.

3. In this way thin paraffin sections free from preformed phosphate are obtained.

4. Phosphatase is demonstrated by the Gomori-Takamatsu (1939) technique.

5. Long bones, ribs, and membrane bone from the skull of adult rats and mice and of new-born kittens were examined.

6. Phosphatase was found to be present in the endosteum, the inner layer of the periosteum, the Haversian canals and linings of vascular and marrow spaces, the nuclei of bone marrow and connective tissue-cells, and in isolated osteocytes. The hypertrophic cartilage was positive in both nuclei and matrix in the rodent bones but negative in the kitten bones. The bone matrix and the small-celled cartilage were negative throughout.

7. The possible significance of these findings in relation to the function of alkaline phosphatase is discussed.