Yohichiro Nozaka

Scanning electron microscopic observations of the basement membranes with dithiothreitol separation.

Scanning electron microscopic (SEM) studies of the interstitial surface of the lamina densa can be performed with dithiothreitol separation, which is the only method of exposing this surface. SEM observation revealed the three-dimensional structures of the meshwork in the lamina densa and anchoring fibrils in dithiothreitol-separated specimens. Detection of the components of the basement membrane can be performed by immunoscanning electron microscopy on this exposed surface by comparing the backscattered and the secondary electron images. SEM observation also revealed the fine structure of the lamina fibroreticularis using separated dermis or the lamina propria mucosae.

Regeneration of Mouse Lip Epidermis after Cryo Treatment

The processes of degeneration and the regeneration of the lip epidermal cells was observed by electron microscopy, focussing on the substance and the structure of the lamina lucida, on which regenerating cells migrated. After the repetitive freezing and thawing treatment, epidermal cells degenerated and detached from the dermis. The separation occurred between the epidermal cells and the basement membrane, leaving a small amount of cell debris on the lamina densa. After the separation of the epidermis, there were some thick parts in the lamina densa which appeared to be the part below hemidesmosomes. Regenerating epidermal cells migrated from the nondegenerated area along the cellular surface of the old lamina densa. They migrated over the cell debris which was gradually phagocitized, and formed new hemidesmosomes with the old lamina densa. Regenerating epidermal cells did not make close contact with the old lamina densa during their migration, but there was a clear space in between, indicating that some of the materials and the structure of the lamina lucida of the old basement membrane was preserved. By immunoelectron microscopy using anti-HSPG (heparan sulfate proteoglycan) antibody, it became clear that after the epidermal separation, HSPG was preserved in the basement membrane to some extent, especially in the thick parts of the lamina densa located below. The immunoelectron micrographs support the view that hemidesmosomes may reform at the previous locations at the old lamina densa.

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

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.

Long root of deciduous anterior teeth

A 24-year-old female Japanese patient presented with remarkably long roots of retained deciduous anterior teeth and permanent anterior teeth in the upper and lower jaw. Four lower anterior teeth were extracted for esthetic reasons. The patient had no apparent clinical syndrome related to the teeth or jaw, nor did there appear to be a family history of this condition. The extracted teeth and their lengths were as follows: the lower right deciduous lateral incisor was 25.55 mm long (root length, 18.95 mm); the lower left deciduous lateral incisor was 22.10 mm long (root length, 17.25 mm); the lower right deciduous canine was 27.95 mm long (root length, 20.60 mm); and the lower left deciduous canine was 23.90 mm long (root length, 17.65 mm).