Histochemistry 29 



a cell proportionately, and in any case some such mechanism must 

 be present to allow the entry of macromolecules (e.g. antibodies) 

 into cells. However, a process of this kind cannot explain the 

 highly selective transfer of ions into and out of cells. On the other 

 hand, the reverse process of granule and vacuole extrusion at the 

 apex of the cell seems to be a quite general and fundamental 

 phenomenon in secreting cells. 



HISTOCHEMISTRY 



PAS-Schiff reaction. In all species so far examined amylase- 

 resistant PAS positive material is present in the acinar cells. This 

 is often present in higher concentration in cells classified as mucous 

 than serous, although for instance the "special" serous cells of the 

 mouse submaxillary gland are stained more strongly than the ser- 

 ous cells of the parotid. Staining is not prominent in the ducts but 

 in the apical region of the intralobular ducts small intensely stain- 

 ing granules are present (mouse), some of these being seen in the 

 cell margin and in the lumen either free or attached to the cell 

 membrane. The duct cells contain much glycogen (i.e. PAS 

 material removed by amylase) (Junqueira, Fajer, Rabinovitch and 

 Frankenthal, 1949; Hill and Bourne, 1954; Lewke and Miiller, 

 1956; Shklar, Glickman and Turesky, 1958). 



Phosphatases. Alkaline phosphatase is present irregularly in the 

 salivary glands (Noback and Montagna, 1947; Deane, 1947; Jun- 

 queira et ah, 1949; Hill and Bourne, 1954). Leeson (1956) found 

 the alkaline phosphatase reaction of rat salivary glands (Gomori's 

 technique) localized almost exclusively to the myoepithelial cells, 

 otherwise only irregular appearance of alkaline phosphatase was 

 found. Acid phosphatase was found in both duct and acinar cells 

 in the rabbit, but was scanty in the mouse, rat and cat. In the 

 guinea pig parotid there was a strong concentration of the enzyme 

 at the apical surface of the striated duct cells. 



Esterases. Cholinesterase is found mainly in the nerve fibres of 

 the salivary glands. These are particularly seen surrounding the 

 main ducts. The enzyme also appears as a fine network around the 

 base of the acinar cells. Small amounts were also seen in the nuclei 

 and cytoplasm of the duct cells. The density of stained nerve fibres 

 was much less in the sublingual than in the submaxillary gland 

 (Snell and Garrett, 1957). 



Esterases detected with naphthyl acetate and naphthyl AS acetate 



