Quarterly Journal of Microscopical Science, Vol s3-91, 315-330, Copyright © 1950 by Company of Biologists

An Investigation of the Histochemical Technique for the Localization of Acid Phosphomonoesterase

¹ Department of Zoology and Comparative Anatomy, Oxford

1. A method is described for assessing the depth of ‘staining’ obtained with the acid phosphatase technique and a detailed scheme is given of the standard technique used.

2. It is concluded that the technique specifically demonstrates the activity of acid phosphatase, since ‘staining’ is abolished in the absence of substrate, in heated sections, and in the presence of fluoride.

3. An investigation has been carried out to determine the extent to which the reaction is affected by altering various stages in the technique.

4. The effect of formalin fixation on the reaction has been investigated.

5. It has been shown that sites in the rabbit medulla having an affinity for the reagents used in the technique differ from the sites at which a precipitate is deposited as a result of enzyme activity.

6. Evidence is presented suggesting that the technique may not demonstrate the true physiological localization of the enzyme.

7. It is suggested that the technique may be of value as a neurohistological method.