Morphology and histochemistry of rabbit submandibular glands

The rabbit submandibular glands are of the heterocrine type. The most distal part of the ductal system consists of secretory endpieces, which are constructed mainly of two morphologically and histochemically different and distinct structures: distally the seromucous acini and proximally the serous tubuli. The cells of the seromucous acini are strongly AB pH 2.5 positive, AB pH 1.0 negative and PAS negative, indicating production of acid glycoproteins--mainly sialomucin. The cells of the serous tubuli are AB pH 2.5 negative and strongly PAS positive, indicating the presence of neutral glycoproteins. Glycol methacrylate embedded sections (Historesin) stained with a modified Trichrome stain were superior to standard paraffin sections regarding resolution and clarity of morphological details. Quantitative studies of intralobular structures on AB-PAS-stained paraffin sections compared with Trichrome-stained glycol methacrylate sections gave corresponding results. The latter method is well suited for study of structural changes in submandibular glands, as in assessing the effect of ionizing irradiation.