The histochemical and microscopical differentiation of the respiratory glands around the maxillary sinus of the rat

To investigate the histochemical and microscopical characteristics of the lateral and maxillary glands, as well as their topographical relationship with the maxillary sinus, 25 adult specimens were used. The tissues were fixed in neutral buffered formalin and serial sections were stained with hematoxylin and eosin, trichrome, Sudan black B, ninhydrin-Schiff, PAS, alcian blue, and mucicarmine. The objectives were to ascertain: (1) the general morphology of the lateral nasal wall and of the maxillary sinus, (2) the topographical relation between the glands and the maxillary sinus, (3) the microscopical and histochemical characteristics of the maxillary gland, and (4) the microscopical and histochemical characteristics of the lateral nasal gland. In all specimens, the sinus was surrounded by glandular tissue. The lateral gland occupied the submucosa anterior and inferior to the sinus, the maxillary gland extended from the anterior to the posterior recess superior to the sinus. The maxillary gland showed the typical morphology characteristic of a serous gland. The gland drained into the sinus by numerous excretory ducts. The epithelium of the proximal ducts was simple columnar and in the distal ducts, pseudostratified columnar ciliated. The latter type of epithelium, without goblet cells, was found in the maxillary sinus. The lateral gland showed a morphology characteristic of mucous glands. Although the gland contained neither free lipids nor proteins, it was PAS-positive. A high concentration of acid glucoproteins was detected in the lateral gland. The excretory system of this gland was lined throughout by either a simple columnar or a simple cuboidal epithelium. The possible contribution of the glands to the functioning of the upper part of the respiratory system was discussed.