CYTOKINETIC ANALYSIS OF THE HUMAN SKIN IN VIVO IN NORMAL AND PATHOLOGIC CONDITIONS: A 3H-THYMIDINE AUTORADIOGRAPHIC STUDY

Abstract

The authors studied DNA synthesis of the human epidermis, the sweat glands and the sebaceous glands by ‘local labeling method’ in using 3H-thymidine and analyzed cytodynamics by ‘migration chase method’. They extended the experiments to analyze the cytokinetics of the epidermis in the pathologic conditions: psoriasis vulgaris, erythrodermia diffusa, eczema chronicum, pemphigus seborrhoicum, regenerating epidermis and keratinized squamous cell carcinoma. The results obtained were as follows.1. The mitotic index of the generative cells of the normal human epidermis (taken from the lateral aspect of forearm) is 0.7-0.8 percent.The labeling index (percentage of the labeled cells) of the generative cells, 1 hour after the injection of 3H-thymidine, is 7 percent.2. The life span of the maturative cells, which consist of prickle and granular cells, was determined by the migration chase of the labeled cells. The life span is 21 days.3. The generative cell compartment consists mainly of the basal cells. The generation time and DNA synthetic time of the generative cell is about 4.2 days and 7 hours, respectively.4. The generative cells as well as the maturative cells form a cell compartment with fairly constant cell number. Th generative cell compartment and the maturative cell compartment have specific turnover rate independently of each othor. The number of cells which constitute the normal epidermis are almost constant.5. In the case of psoriasis vulgaris the generative cell compartment and the maturative cell compartment are expanded.The generation time of the generative cells and the life span of the maturative cells are shortened and become about 17 hours and about 5 days, respectively. The data indicate more rapid migration of the maturative cells in the psoriatic epidermis than in the normal one.6. The rapid cell renewal of the epidermis of the psorasis vulgaris seems to be responsible for the hyperkeratotic and parakeratotic symptoms.7. The DNA synthetic index or the labeling index of the generative cells of the other pathologic epidermis: eczema chronicum, erythrodermia diffusa and pemphigus seborrhoicum were calculated. And the cytodynamics in these conditions was analyzed.8. The regenerative cellular proliferation was observed 36 hours after epidermal injury in the 3H-thymidine autoradiograph taken 1 hour after the local labeling. The zone of the regenerative cellular proliferation spread to distal area from the lesion focus with the lapse of time.9. The keratinized squamous cell carcinoma of the glans penis was labeled with local injection of the 3H-thymidine. The result was discussed with special reference to the cellular proliferation and the cell compartment formation. The mode of the cytodifferentiation in the squamous cell carcinoma is qualitatively similar to the normal epidermis.10. The DNA synthesis of the eccrine and apocrine sweat glands and the sebaceous gland were studied.The generative cell compartment of the sebaceous gland consists of the most external monocellular layer.The generative cells of the sebaceous gland lose DNA synthetic capacity as they mature and are pushed into the central part of the gland.11. The differentiation of the epidermal cell seems to be determined during pre synthetic phase (t1) of the generation cycle while the generative cells migrate to the maturative cell compartment from the generative cell compartment.Thus the determination of the cytodifferentiation is not related to the mitosis.