[Histological observation of mucous epithelium of rat antemolar palatal rugae--shape of epithelial-connective tissue junction and structural characteristics of basal and spinous cell layer].

UNLABELLED: The mucous epithelium of the rat palatal rugae was observed by light and electron microscopy. The shape of the epithelial-connective tissue junction (ECJ) of the rat palatal mucosa was found to be composed of ridge-type papillae (RTP) which ran in an antero-posterior direction (APD). The purpose of the study is to investigate the differentiation of the basal and spinous layer in the palatal mucosa which consists of RTP by the observation of the shape of the ECJ and the morphology and structure of the constituent cells. RESULTS: (1) The RTP which ran in the APD appeared to be related to the direction of the blood vessels and collagen bundles within the submucous and papillary layers. (2) The basal cells were classified into B1, B2 and B3 cells for the sake of convenience from the morphological and structural characteristics. Polyhedral spinous cells located within the lower third of the spinous layer were also classified into S1P and S11 cells. (3) The B1 and S11 cells were mainly distributed in the inter-papillary area (1-area), the B2 and S1P cells in the papillary area (P-area) and the B3 cells between the P- and I-area (PI-area). (4) The cell division was observed chiefly in the I- or PI-area in the APD and the divided cells appeared to become B1 cells. The B1 cells transitionally changed into B2 or B3 cells and finally into S1P cells in the P-area, and S1I cells in the I-area.