Abstract: In order to understand the pathological course of vitiligo and explore its pathogenesis further,we studied ultrastructural characteristics of ten cases of progressive vitiligo with transmission electronmicroscope.Biopsies were obtained from the center and margin of the lesion,and clinicaly nor-mal skin on the symmetrical part of the body.The results showed that melanocytes and melanosome were absent in the center of the lesion in nine cases;a residual degenerated melanocyte was seen in one case.In the margin of the lesion many abnormalities were observed,the most significant changes in melanocytes were dilatation of rough endoplasmic reticulum and degeneration of melanosome;keratinocytes also showed degenerative changes,Langerhans' cels were active and increased in density.Qualitative and quantitative studies showed that the clinically normal skin had pathological changes already.This report shows that ultrastructural changes in the margin of the lesion are most evident,three types of cells in the epidermis including keratinocytes,melanocytes and Langerhans' cells are degenerated,the clinically normal skin far away from the lesion is abnormal and is posibly under subclinical state.Cell morphometry turns cytologic study from qualitative to quantitative study,it is worthy to be used.

Key words: Vitiligo, Microscopy,electron