Scanning electron microscopic studies of the palatine mucosa and its microvascular architecture in the rat.

Detailed observations were made on the structure and microvasculature of the palatine mucosa of the rat by means of microvascular corrosion casts and epithelium-digested specimens using scanning electron microscopy. The rat palate was divided into four regions according to the characteristics of the palatine plicae. In the atrial region, no transverse palatine plicae were present, but there were longitudinal ridges and folds in the median area. These structures contribute to the transportation of rough and grainy foods with the assistance of the hairy buccal part. Capillary loops in the ridge and folds appeared as continuous, sagittally elongated loops. In the palatine fissure or antemolar region, only three typical transverse palatine plicae contribute to the regurgitation of food. Capillary loops appeared in variant forms on the top, and the anterior and posterior slopes of the plicae. Venous palatine plexus was observed only in the palatine fissure region. In the intermolar region, each of the five transverse plicae was composed of many wedges arranged sagittally. These plicae contribute to the transportation of food toward the larynx. Capillary loops in the plica were in the shape of complicated villi. Filiform protrusions or papillae were aggregated immediately posterior to the last plica. The capillary loops appeared as typical hairpins. They contribute to swallowing of food with active assistance from the epithelial eminence of the lingual dorsum. Palatine plicae showed considerable local differences, which may contribute to the prehension, transportation, and mashing of food.