Morphological investigations of the glandulae profundae plicae semilunares conjuctivae in the domestic swine (Sus scrofa domesticus) and the wild hog (Sus scrofa ferus).

Samples of glandulae profundae plicae semilunares (Harderian glands) from five domestic swine and five wild hogs were used for this research. The gland samples were fixed in Bouin solution and mounted in paraffin. The paraffin slices were stained with haematoxylin and eosin, according to the periodic-acid-Schiff (PAS) method, with alcian blue (pH 2.5), with toluidine blue (pH 4.0), and applying a combination of staining with alcian blue (pH 2.5) and the PAS method. In domestic swine and wild hogs, these glands are tubular-alveolar with wide glandular lumina. A great deal of acid mucopolysaccharides and PAS-positive substances were noted within swines' glandular cells, while, in wild hogs, PAS-positive substances were not frequent, acid mucopolysaccharides being noted in only a few glandular-acini cells. The appearance of the metachromatic phenomenon was not noted either in domestic swine or in wild hogs. In domestic swine, the level of acid mucopolysaccharides is probably due either to the housing method or to the influence of the alkaline substances that may appear on an eye's mucous conjunctive membrane during intensive breeding, such that the Harderian glands protect the mucous membrane by extracting acid mucopolysaccharides.