The Localization of Phosphatase in Cells in Tissue Cultures

In a recent paper, Gomori (1941) has described a histochemical method for the localization of phosphatase in animal tissues. The method depends on the fact that the enzyme is not destroyed by moderate treatment with 80 % alcohol, in which the tissues are fixed. After fixation the tissues are sectioned; the sections are incubated with sodium glycerophosphate and calcium chloride in buffered-solution and calcium phosphate is deposited at the site of phosphatase activity. This can be rendered visible by treatment with cobalt nitrate solution followed by ammonium sulphide, when the site of the phosphatase is marked by a black precipitate. By the use of such methods he has described, among other things, the occurrence of phosphatase in capillary endothelial cells in different animals, not with absolute regularity, but in a large number of cases. In those instances in which a positive reaction was not obtained it was shown to be an idiosyncrasy of the particular tissue rather than a failure of the method. It seemed possible therefore that an attempt to separate endothelial cells from other mesenchymal cells growing in vitro might be assisted by the use of this method.