Histomorphological and histochemical study of the major salivary glands of adult local rabbits

The study aim to investigate histomorphological and histochemical structures of three major salivary glands in the adult local rabbits, that are parotid, submandibular and sublingual glands. To conduct that, twenty four adult local rabbits of both sexes are used. Macroscopically, all of the major salivary glands were paired and that the parotid was the largest compared to the submandibular and sublingual glands and the latter, was the smallest of these gland. Microscopically, parotid showed purely serous acini only in its constituting glandular tissue. Whereas, the other glands were mixed in which the submandibular was formed of mucous, serous and few demilune, but sublingual gland showed mainly mucous acini and many demilune only. The intralobular parenchymal tissue was very packed in case of submandibular gland, but for lower extent in parotid and for the lowest in sublingual gland. Characteristically, the microscopic sections from submandibular glands were showed higher number of intralobular ducts compared to those observed in the parotid and sublingual glands. Histochemical staining procedures were indicated various reactions of the glandular acini of these glands toward the different used stains in this study. Significantly, parotid acini were reacted positively with PAS stain, but did negatively with AB and combined AB-AF stains, because the gland was fully serous and no mucin could be detected in their acini. Similarly, submandibular showed PAS positive reaction. In addition to that the combined AB-PAS also showed positive reactions by the appearance of the blue and magenta colors to both stains, respectively. It indicated the presence of acidic and neutral mucins. Sections stained with AB showed dark blue staining indicated that their mucins of non sulfated type. Moreover, the combined AB-AF stains revealed positive reaction to AB but not the AF indicating the presence of acidic non sulfated mucin constituent in nature. Sublingual glands showed positive reaction with the PAS stain characterized by magenta color formation of its mucinous contents. In another hand, the combined AB-PAS stains also showed positive magenta color toward the PAS, but negatively reacted with the AB, indicated the absence of the non sulfated mucin. Whereas, AB-AF stains showed positive dark purple reaction due to AF stain, but not reacted with the AB part of the stain. Such findings indicated the presence of sulfated mucin in their constitutional acini.