The distribution of Langerhans cells in the dorsal mucosa of the mouse tongue.

Abstract

Ultrastructure and distribution of Langerhans cells in the dorsal mucosa of mouse tongue were observed by light and electron microscopy and by ATPase histochemistry. The epithelium could be divided into papillary and interpapillary parts. Both papillae and interpapillae were orthokeratinized. The differences between the two parts were mainly due to the cellular characteristics of the prickle cell layer, granular layer and keratinized layer. In the interpapillae, tonofilaments in the cytoplasm of the prickle cells evenly dispersed without forming bundles, and the desmosomes were observed more clearly. The granular layer was less developed than that of the papillae. The cytoplasm of the keratinized layer stained with toluidine blue more lightly than that of papillae. By light microscopy, cells with clear cytoplasm occurred in the prickle cell layer just above the basal cell layer of interpapillae. They extended long cytoplasmic processes vertically, up to the granular layer and down to the basal layer. ATPase-positive dendritic cells were distributed in the interpapillae. By electron microscopy, Birbeck granule-containing Langerhans cells were observed in the interpapillae. The dendritic cells, which were observed as cells with clear cytoplasm by light microscopy or as ATPase-positive cells, agreed in morphology and distribution with the Langerhans cells which were observed by electron microscopy. In dd mice, ATPase-positive Langerhans cells were not observed at 2 weeks after birth, whereas they were observed at 3 and 4 weeks.