REMODELING OF THE DUCT SYSTEM OF THE RAT SUBMANDIBULAR SALIVARY GLANDS IN CHRONIC ETHANOL INTOXICATION

The aim: To determine the dynamics of changes in metric parameters of the duct system of rat submandibular glands in normal conditions and chronic ethanol intoxication. Materials and methods: 50 albino outbred rats were involved in the experiment. 10 animals were assigned in the control group, 40 animals – in the experimental group. Animals were sacrificed on 5, 9, 12 and 30 days by overdose of thiopental anesthesia. Pieces of the submandibular glands were embedded into epon-812 according to the conventional technique. Results: On day 5 of the experiment the lumen diameter of intercalated duct reduced by 9,15 % (р <0,05). The lumen diameter of the striated ducts was by 5,29 % significantly greater than the values in controls (р <0,05). The lumen diameter of the granular ducts reduced by 2,45 % (р <0,05). On day 30 of the experiment the height of the epithelial cells of the intercalated ducts was by 8,47 % significantly less (р <0,05), the height of the epithelial cells of the striated ducts was by 12,27 % less (р <0,05) and the height of the epithelial cells of the granular ducts was by 11,96 % less (р <0,05) than the values in controls. Conclusions: No recovery of parameters occurs by day 30 of the experiment, indicating the depletion of the secretory epithelium of the duct system, due to dystrophic changes caused by vascular disorder in the microvasculature.

Intraspecific Differences Regarding Granular Polymorphism in Granular Ducts’ Cells in Rats’ Mandibular Gland

Mandibular gland ducts’ system in rodents consist of intralobular ducts (intercalated, granular, striated) and interlobular one (main excretory duct). Granular ducts are located between intercalated and striated ducts, being present only in mandibular gland of the mouse, rat, hamster and gerbil. The biological material used for this study was represented by two strains from the same species, three Wistar rats and three Brown Norway rats. After the animals were euthanized, the mandibular glands were harvested and then processed for histological investigations. The tissue fragments were sectioned at 5μm thickness and then stained the sections using Tricrom-Goldners method. Our results emphasize that the granular ducts are well developed; regarding the shape, they are convoluted in both Wistar and Brown Norway rats, without any significant differences between the two strains. In Wistar rat, the granules in granular ducts cells are small to medium in size, with discrete polymorphism. In Brown Norway rat, the cytoplasm is loaded with granules as in Wistar rat, but these are several times larger and more polymorphic.

Presence of Granular Ducts in Mandibular Gland in Rabbit

The present study focuses on the intralobular ducts present in rabbit mandibular gland, from a histological and histochemical point of view. We harvested mandibular gland samples from five rabbits (approximately six month old), which were paraffin embedded and subsequently stained for histological investigation with hematoxylin-eosin. PAS and Alcian blue reactions were used for histochemical assessment. Results show that mandibular gland in rabbit contains one type of acini, namely serous. Concerning the intralobular ducts, there were three types identified: intercalated, granular and striated. Granules present in the cytoplasm of the cells lining the granular ducts appear acidophilic on hematoxylin-eosin staining procedure. Histochemically, granular cells present a moderately PAS positive material (meaning they secrete neutral mucosubstances) and negative staining to Alcian blue reaction (no acid and sulfated mucosubstances were detected). We highlighted the presence of granular ducts in rabbit mandibular gland, which synthesize neutral mucosubstances according to the histochemical reactions applied.

Assessing the intralobular ducts in mouse mandibular gland

In order to quantify the types of intralobular ducts, we used five adult male mice, sacrificed by cervical dislocation, after exposure to anesthetic. After euthanasing the animals, the mandibular glands were histologically processed. We sectioned the tissue at 5 µm thickness and stained the slides using Goldner’s trichrome staining procedure. We captured images on four different microscopic fields for each animal, subsequently counting each type of intralobulary duct. The granular ducts were the most numerous, followed by the intermediary ones and striated ducts with the lowest number.

The istant changes of the salivary glands to stress

Night lighting and microwave exposure have been influence on structures of stress realization. The endocrine, fotoperiodical and adaptive functions of rodent submandibular salivary glands belonging to hormone produced duct cells. To evaluate their morphofunctional state at guinea-pigs and rats using the methods of light and electron microscopy there have been analyzed striated and granular ducts. It has been revealed that instant and twenty-four-hour strengthening of duct cell stress induced secretory activity was similar. It is concluded that salivary glands take part in circadian expectations to stress.

Expression of plasmid DNA in the salivary gland epithelium: novel approaches to study dynamic cellular processes in live animals

The ability to dynamically image cellular and subcellular structures in a live animal and to target genes to a specific cell population in a living tissue provides a unique tool to address many biological questions in the proper physiological context. Here, we describe a powerful approach that is based on the use of rat submandibular salivary glands, which offer the possibility to easily perform intravital imaging and deliver molecules from the oral cavity, and plasmid DNA, which offers the advantage of rapid manipulations. We show that, under different experimental conditions, a reporter molecule can be rapidly expressed in specific compartments of the glands: 1) in the intercalated ducts, when plasmid DNA is administered alone, and 2) in granular ducts, striated ducts, and, to a lesser extent, acini, when plasmid DNA is mixed with replication-deficient adenovirus subtype 5 particles. Remarkably, we also found that gene expression can be directed to acinar cells when plasmid DNA is administered during isoproterenol-stimulated exocytosis, suggesting a novel mechanism of plasmid internalization regulated by compensatory endocytosis. Finally, as a practical application of these strategies, we show how the expression of fluorescently tagged molecules enables the study of the dynamics of various organelles in live animals at a resolution comparable to that achieved in cell cultures.