Histochemical characteristics of mucopolysaccharides in salivary and exorbital lacrimal glands

Abstract

Comparison of results obtained by S³⁵O₄= autoradiography with those from histochemical staining methods and evaluation of the effect on the staining resulting from prior sialidase digestion, methylation, methylation and saponification, or sulfation, substantiates the selectivity of some procedures for sialomucin and others for sulfomucin. These two types of mucopolysaccharide may be differentiated by the high iron diamine‐alcian blue or aldehyde fuchsin‐alcian blue sequences or comparison between staining with the alcian blue pH 2.5‐PAS sequence and staining with the alcian blue pH 1.0‐PAS method. These techniques reveal that some rodent or lagomorph salivary glands form sialomucin alone, others apparently only sulfomucin, whereas a number produce both types of acid mucopolysaccharide either in different mucous cells throughout the gland or in the same cell.Differences in affinity for basic dyes, periodate reactivity, and susceptibility to elimination of basophilia by methylation or enzymatic digestion are evident among both the sulfo‐ and the sialomucins in different glands. After brief saponification the sialomucin in rat sublingual glands becomes sialidase digestible and gains alcohol resistant metachromasia.Several serous or seromucous glands secrete neutral mucopolysaccharides; others secrete polysaccharides containing sulfate or sialic acid groups whose affinity is masked for some but not for other basic dyes.