1985 Volume 24 Issue 4 Pages 620-631
We report on ultramicroscopic observations of GAK cultured cells from an inguinal lymphnode metastasis which had originated from a malignant melanoma of the vulva. Approximately 2 months after GAK cells were injected into a nude mouse, a tumor was produced in the abdomen which was subsequently examined ultramicroscopically. The cells were examined ultramicroscopically, with the main emphasis on melanogenesis, employing the premelanin, dopa, and dopa-premelanin double reactions. The following results were obtained.
1. In the GAK cultured cells and the transplantation tumor cells from the mouse, melanosomes in various stages of melanogenesis were observed. Both the GAK cells and the nude mouse tumor cells were found to be in an active state of melanogenesis. An axon body-like structure was observed, indicating the tumor cells probably were derived from neurogenic tissue. Furthermore, the premelanin reaction revealed not only electron dense melanosomes but also electron dense premelanosomes, the latter of which are a product of an earlier stage of melanogenesis. The positive dopa reaction proved the activity of tyrosinase and that the tyrosinase was the melanin-producing enzyme. Tyrosinase activity was observed ultramicroscopically in the Golgi associated endoplasmic reticulum-lysosome (GERL)-like structure which had previously been proven by biochemical studies and stereostructural analysis.
2. The cells had ultramicroscopical characteristics which were unlike those of epithelial or non-epithelial cells, suggesting they were most likely derived from neural crest tissue.
3. Intranuclear vacuoles, which are very often found during cytological examination of malignant melanomas, were in this case, proven ultramicroscopically to be due to cytoplasmic intranuclear invagination. The intranuclear vacuole was readily observed due to the rough, irregular shape and deep indentation of the nuclear membrane and the plane of sectioning used.
