[Ultrastructural changes of endoplasmic reticulum in malignant keratinocytes of laryngeal carcinoma]

The alterations in ultrastructure of the endoplasmic reticulum (ER) in squamous cell carcinomas of the larynx were studied by electron microscopy. In some malignant keratinocytes the ER cisternae become aggregated into stacks forming paired or compound ER. If two or more ER elements aggregate, the inner apposing lamellae lose their ribosome particles. Simultaneously, the electron density of the inner lamellae and of the intercisternal material increases. These paired ER cisternae can frequently be observed associated with the nuclear envelope in mitotic cells, but they can also occur in interphase cells. C-shaped paired ER profiles in association with mitochondria and various cylindrical ER structures were also observed. Further, dilation, vesiculation, disorganization, and association of the ER with different cytoplasmic organelles was also seen. The observed results are compared with other reported ER changes and the significance of these changes in the neoplastic ergastoplasm is discussed.