Use of scanning electron microscopy for the study of human epidermal melanocytes

Scanning electron microscopy of frozen-cracked, dry-cracked and enzyme-digested tissue of human malignant choroidal melanomas

By applying cracking and enzyme-digestion methods to tissue of human malignant choroidal melanomas, SEM was used to visualize the interior of the cells, their membranes, nuclei and organelles. Single cells were depicted to their full extent. Apart from a three-dimensional impression of the structures and their surfaces, the methods also made it much easier to measure cells and cell components than by conventional methods.

The epidermal melanocyte system in individuals of Scandinavian origin, determined by DOPA-staining and TEM

The quantitative evaluation of DOPA-positive epidermal melanocytes in 16 patients of Scandinavian origin showed both individual and regional differences in the melanocyte count. Our data is in agreement with other published studies. The distribution in the number of melanocytes varies significantly in some specimens. This is due partly to the preparation procedure and partly to normal biological variations. We believe that we have demonstrated a cyclic function of the melanocyte in the epidermis. The varying density of cells in epidermal sheets as well as their varying morphology support the theory concerning the presence of the epidermal melanin unit.

Cutaneous malignant melanoma. Studies on the find structure of cells and their surface morphology in relation to tumour type and clinical course

Cutaneous malignant melanoma occurs in three forms: lentigo maligna melanoma, superficially spreading melanoma, and nodular melanoma. The histology, the clinical development and the biological malignancy of these tumours differ. The purpose of the study reported here was to provide a clearer picture of the surface morphology of the malignant cells and to relate their fine structure to both the tumour type and the clinical development of the malignant melanoma. This investigation of 28 tumours from 22 patients of Scandinavian origin shows that at the electron microscope level there is no difference between malignant cells in the invasion nodulus of superficially spreading melanoma and nodular melanoma. The primary tumours were often built up of 2 or 3 differently differentiated cell clones. Metastases were built up of the same cells or cell clones that were found in the primary tumour. In several cases the surface of the malignant cells was folded, and covered with microvilli, microblebs and blebs. These surface alterations could be related in several cases to changes in the cytoskeleton of the cell (microtubuli and microfilament complexes). The clinical course of the malignant melanoma could best be correlated to the histogenetic type of tumour, depth of invasion, nucleus polymorphy and the quantity and arrangement of the microfilament complexes.

The epidermal melanocyte system in patients with malignant melanoma. Quantitative and qualitative investigation of dopa positive melanocytes

The results from this study indicate that in 5 out of 22 patients increased activity of the melanocytes in the vicinity (a few mm to 1 cm) of the tumour is to be found. In 8 out of 22 patients suspect cells were also found a few mm to 1 cm from the tumour; a finding which accounts for the frequent recurrence following close excision of the melanoma. Furthermore, it was ascertained that the total melanocyte population is increased in 14 out of 22 patients. An increased melanocyte population can contain a greater number of instabile cell forms that can easier be malignantly transformed under the influence of external factors.

The epidermal melanocytes in patients with cutaneous malignant melanoma. A transmission electron microscopic investigation

The epidermal melanocytes were studied in biopsies from clinically normal skin removed at various distances from cutaneous malignant melanomas. Melanocytes with some ultrastructural changes were found in a number of patients, which can be either contingent on genetic or inter/extra cellular factors. It is possible that cells with these changes are more instable and more easily transformed to malignant cells by external influence. Malignant cells were not demonstrated in either the epidermis or the dermo-epidermal junction. Activation was seen of the epidermal melanocytes lying in the immediate neighbourhood of the superficially spreading melanomas, which would suggest that this type of tumour is presumably able to influence the melanocytes. The most pronounced changes in the whole of the melanocyte system was found in patients with multiple melanomas, and in a patient with metastasizing malignant melanoma.

The surface morphology of the melanoma cell. A scanning electron microscope study on the primary cutaneous melanoma

The surface morphology of the melanoma cell in situ is summarized with regard to a study undertaken to elucidate the appearance of melanocytes and their differentiation in the surroundings of the malignant melanoma. Despite a non uniform cell pattern, several characteristic changes were found. The cells were 2-3 times the size of normal melanocytes, a number being differentiated by dendrites. The surface of the cell was marked by a numerous extensions, a number of which had differentiations that indicate a special function, though some smooth-surfaced cells were also found. It is possible that cell surfaces with many bulges and extensions are an expression of an unstable, undulating surface which could be of significance for the uncontrolled growth and metastasis of tumours.