A comparative lectin histochemical study of major and minor salivary glands with special reference to the labial glands.

There is debate about the nature of the secretory cells in labial salivary glands. To characterize their basophilic acini the binding patterns of different lectins were examined in these glands (n = 30) and compared with those of major salivary glands (n = 10) and palatal salivary glands (n = 20). Binding in formalin-fixed paraffin-embedded sections was revealed using either anti-lectin antibodies and the peroxidase-antiperoxidase method or biotinylated lectins and the avidin biotin method. Binding of peanut agglutinin was seen in all basophilic acini of labial glands, whereas serous acini of major glands were completely negative. Focal binding of soybean agglutinin was seen in all basophilic acini of labial glands in addition to diffuse binding in mucous acini of all salivary glands, whereas serous acini were mostly negative. Conversely, there was binding of Ulex europaeus agglutinin I in all mucous and serous acini of all glands except for the basophilic acini of labial glands. Bandeiraea simplicifolia agglutinin I and Helix pomatia agglutinin bound to all basophilic and most mucous acini of labial glands, and to most mucous acini of major salivary glands, whereas only a few serous acini of major glands were reactive with both lectins. Pretreatment with neuraminidase yielded binding sites for peanut agglutinin in most of the serous acini of major glands and mucous acini of labial glands, and increased B. simplicifolia agglutinin I and H. pomatia agglutinin binding in the serous acini of major glands. Thus the different lectin binding patterns, particularly the differences in the reaction patterns of peanut, soybean and U. europaeus agglutinin I, showed that the basophilic acini of labial glands reacted more like mucous acini.