This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Nathaniel, E. J. H. Articles by Rychuk, H. Search for Related Content PubMed PubMed Citation Articles by Nathaniel, E. J. H. Articles by Rychuk, H.

Electron Microscopic Observations on Cells of Harding-Passey Melanoma following Colchicine Administration¹

Department of Anatomy, McGill University, Montreal, Canada Division of Laboratories, Cedars of Lebanon Hospital, Hollywood, California, and Department of Pathology, Medical College of Georgia, Augusta, Georgia

Electron microscopic studies were undertaken on control and colchicine-treated Harding-Passey melanoma tumors in the mouse. The tumor cells in untreated animals were pleomorphic. Nuclei generally were irregular, with moderate to heavy accumulation of chromatin. Cytoplasm was rich in free and attached ribosomes. Tubulovesicular mitochondria were present in interphase melanocytes. The mitotic melanocyte was composed of a central component of ribosomes, in which were located chromosomes, and a peripheral part, made up of dilated cisternae of endoplasmic reticulum. Type A virus particles were encountered in relation to the endoplasmic reticulum of many tumor cells. Intercellular attachments were not visualized.

A significant feature of colchicine-treated tumor cells was the appearance of filaments measuring 35–50 Å in diameter in both nonmitotic and mitotic cells. These filaments possessed a close spatial relationship to the ribosomes, suggesting their possible origin from the latter. The filaments appeared morphologically similar to tonofilaments; hence they were considered to be prekeratin. In addition, several tumor cells exhibited localized thickening of their membrane, indicating junctional arrangements.

It is therefore hypothesized that the treatment of Harding-Passey melanoma with colchicine has induced an altered type of differentiation in melanoma tumor cells.

¹ Supported in part by USPHS Grants NB 05850 and HE 09126. Part of the work done at McGill University was supported by a grant from the National Cancer Institute of Canada to Dr. C. P. Leblond.

² Present address: Department of Anatomy, McGill University, Montreal, Canada.

Received 6/12/67. Accepted 2/12/68.