The histochemistry of carbohydrate-rich substances in certain ungulate salivary glands.

Abstract

AbstractThe carbohydrate‐rich secretions of bovine, ovine and porcine submandibular and sublingual glands have been investigated histochemically. The strong PAS staining of mucous acini in all the glands indicates presence of mucin rich in residues with vic‐glycols. This staining correlates well with the neutral sugar (hexose or deoxyhexose) content except in the bovine submandibular gland in which other types of residues as perhaps C‐6 linked or terminal amino sugars with vicinal hydroxyls apparently account for PAS staining. Strong staining with a periodate‐para diamine procedure is observed only in the glands with high hexose or deoxyhexose levels and is absent from those with strong PAS reactivity apparently attributable to amino sugars. Digestion with malt diastase diminishes the PAS staining of a mucous secretion in mucous acini of the sheep glands.The mucous acini of the submandibular glands form sialomucin uniformly and afford no evidence for the presence of a sulfomucin. The basophilia of this sialomucin in sow and ewe is fully susceptible to sialidase. Sialomucin basophilia in the bovine submandibular gland is only partially digestible, indicating presence of two kinds of neuraminic acid or two sialomucins in this gland.In the sublingual glands the proportion of sulformucin to sialomucin increases in the order cow‐sow‐ewe. The sialomucin in the bovine and porcine sublingual mucous acini revealed as blue‐stained material with the high iron diamine‐alcian blue sequence largely succumbs to sialidase. Much of that similarly demonstrated in the ovine sublingual gland resists digestion, suggesting presence herein of two sialomucins. The sialomucin in all the mucous acini of the ovine submandibular and some mucous acini of the ovine sublingual glands loses azurophilia and undergoes marked decrease in alcianophilia after digestion with malt diastase.Prominent seromucous demilunes in the ovine and bovine glands appear to secrete a sulfated mucosaccharide. The secretion in these sites stains well with the PAS method. The seromucous demilunes in the cow afford evidence also of a mucosaccharide‐containing sialic acid.