212 Microscopic Histochemistry 



Na2S04 for 30 minutes and then incubated with the sub- 

 strate containing the same concentration of DIPFP. 



Sehgman and co-workers^^^ have synthesized three highly 

 interesting naphthoHc substances which closely imitate the 

 steric configuration of acetylcholine. No reports have been 

 published so far on their practical use. 



The Results of Histochemical Methods for Esterases 



Saturated Tweens are hydrolyzed by many tissues; un- 

 saturated ones, only by the pancreas of all species and by 

 the chief cells of the mouse stomach ( "true lipase" ) . 



The localization of enzymatic activity in the case of naph- 

 thoHc substrates is very smiliar to that seen with the Tween 

 technique, except that it is more widespread. A number of 

 sites entirely negative with Tweens stain very intensely with 

 the azo dye method (renal tubules of man; ganglion cells in 

 several species, etc.). On the other hand, there are a few 

 structures which are Tween-positive but naphthol-negative 

 ( spermatic elements of the testis and chief cells of the stom- 

 ach of the mouse ) . Although at most sites the two naphtholic 

 substrates produce identical pictures, there are several ex- 

 amples of true substrate specificity directed toward a-naph- 

 thyl acetate or naphthol AS acetate, respectively. The villi of 

 the duodenum of the rat, certain unidentified cells in the 

 heart of the rat, the septal cells of the mouse lung, etc., stain 

 very intensely with a-naphthyl acetate and faintly, or not at 

 all, with naphthol AS acetate. The reverse holds true for 

 Brunner's glands of the rat, for motor cells of the rabbit and 

 rat, and for human mast cells. The differences are so clear- 

 cut that it is safe to assume the existence of two individual 

 enzymes ( conveniently called "a-esterase'' and "AS-esterase," 

 respectively), characterized by the substrate specificities in- 

 dicated. The pictures obtained with ^-naphthol appear to 

 be identical with those seen in the a-naphthol method; this 



125. Seligman, A. M., Nachlas, M. M., Manheimer, L. H., Friedman, 

 O. M., and Wolf, G.: Ann. Surg., 130:333, 1949; Ravin, H. A., Tsou, Kwan- 

 Chung, and Seligman, A. M.: J. Biol. Chem., 191:843, 1951. 



