Histochemistry and immunohistochemistry of the parotid and submandibular salivary glands in Hystrix indica

The present work was aimed to investigate the histochemical and immunohistochemical features of the parotid and submandibular salivary glands in the porcupine. Three adult male animals were included in the current study. Histochemical properties of the glands were studied using Periodic acid-schif (PAS), Alcian blue (AB) (pH = 2.5), and Aldehyde fuchsin (AF). The expression rate of MUC-, Ck7 and S100 was investigated immunohistochemically. The parotid gland was triangular at the base of external ear, and the submandibular was rectangular and larger than parotid. The parotid duct was passed over the dorsal border of masseteric muscle, however, the submandibular duct was positioned on the ventral border of the masseteric muscle. Histochemically, the parotid gland had mucous acini with positive reaction to AB and AF and so week reaction to PAS. This indicated acidic and sulfated mucous secretion for parotid gland. The submandibular gland was composed of mucous acini that showed negative reaction to AB, AF, and PAS stains. The submandibular gland secretion was a non-acidic and non-sulfated saliva. The MUC1 wasn’t expressed nor in parotid and submandibular glands. Ck7 marker was expressed extensively in ductal epithelial cells of both glands. S100 protein showed wide expression in the myoepithelial cells of parotid gland. However, its expression was rare in submandibular gland. In conclusion, the present findings indicated that major salivary glands in the porcupine have species-specific features. This knowledge would be useful in future studies for deeper understanding of the detailed histophysiology of the digestive system in zoo animals.