| Abstract: | Summary The ultrastructural morphology of the hemidesmosomes in malignant epithelial cells of invasive squamous cell carcinoma of the human larynx was studied by electron microscopy. In the more advanced carcinomas the hemidesmosomes were reduced in number or absent over extensive areas of the epithelialstromal junction. Hemidesmosome-containing areas of the basal plasmalemma were seen to invaginate and to appear to pinch off inwardly. The detached hemidesmosomes rounded up with their cytoplasmic attachment plaque lying on the inner circumference of the vesicular structures and were autophagocytized by the malignant keratinocyte. However the detachment of hemidesmosomes and their subsequent downward migration into the deeper layers of the connective tissue space was observed in other areas. These observations indicate that reduction of hemidesmosomes may result in a loss of epithelial-stromal adherence in invasive epithelial cancer of the larynx and may thus facilitate the tumor invasion of the underlying stroma. |
