Discipline: Veterinary Medicine
The histological and histochemical features of the labial and pharyngeal glands of the Philippine water buffalo were described using hematoxylin-eosin, periodic acid-Schiff (PAS), mucicarmine and alcian blue (AB) pH 1.0 and 2.5 stains. The predominantly mucous labial glands of the Philippine water buffalo were moderately developed. They were found in the lamina propria-submucosa and tunica muscularis as loosely arranged lobes and lobules surrounded by collagen fibers. The duct system consisted of a few intercalated and striated ducts and numerous interlobular and excretory ducts. The secretory units of the labial glands reacted positively to mucicarmine, PAS, AB pH 1.0 and pH 2.5 stains. The pharyngeal glands, on the other hand, were large, consisting of compact lobes and lobules, which were distinctly separated by thick collagen fibers. The glands were purely mucous in the oropharynx and predominantly mucous in the nasopharynx and laryngopharynx. Striated ducts were absent. The glands reacted positively to mucicarmine, PAS, AB pH 1.0 and pH 2.5. Histologically and histochemically, the labial and pharyngeal glands of the Philippine water buffalo resembled, to some extent, those of other species of domestic animals.