Degeneration and Regeneration of the Lip Mucosal Epithelium after Cryo Treatment in Mice

Abstract

The process of degeneration and regeneration of the lip mucosal epithelium after cryo treatment was observed by transmission electron microscopy. The epithelial cells were degenerated by the formation of ice crystals and subsequently detached from the basement membrane, forming a blister cavity. The separation occurred between the epithelial cells and the lamina densa, leaving a small amount of cell debris on the lamina densa. The surviving cells at the periphery of the blister cavity, especially the cells in the basal half of the epithelium, provided the regeneration cells. They migrated over the cell debris, attached to the lamina densa and gradually phagocytozed it. Finally, they formed hemidesmosomes with the old lamina densa. The connections between the epithelial cells by desmosomes were so tight that desmosomes were preserved even between dead cells and between dead and living cells. Regenerating cells were moving in a multilayered form, remaining connected to each other by the dosmosomes. They were seen to divide by mitosis and thereby increase the number of the cell layer, whilst maintaining their connections with the neighbouring cells.