First evidence of histological and histochemical intraspecific differences in salivary glands in Brown Norway and albino Wistar rats

The size of salivary glands, acinar structure, and secretion particularities differ from one species to another and are influenced by diet and environment. In order to investigate whether there are histological or histochemical differences in the salivary glands of animals from the same species, bred in identical conditions of environment and diet, we assessed two laboratory rat strains. The salivary glands from two rat strains were processed for histological and histochemical investigations. Histologically, we noticed differences in the parotid gland: seromucous acini were present in Brown Norway rat and typical serous ones in Wistar rat. Histochemically, we observed that cells in the parotid gland present a moderate PAS-positive reaction only in Wistar rat. In the mandibular gland, the size and shape of the acini were similar, whereas the cytoplasm of acinar and granular duct cells was PAS-positive in both rat strains, but with different intensities. In the sublingual gland, both PAS and Alcian blue reactions were positive in the two rat strains, with a higher intensity in the Brown Norway strain. Our study highlighted intraspecific histological and histochemical differences in salivary glands from two rat strains bred and fed in identical conditions.