Ultrastructure of Three Types of Epidermal Dendritic Cells in Hairless Mice*

Electronmicroscopic studies of epidermal dendritic cells in hairless mice were carried out in normal and pigmented dorsal skin, the latter induced by topical application of DMBA. A quantitative study of three types of epidermal dendritic cells was performed in this series. Statistical evaluation disclosed that: (1) the number of Langerhans cells was inversely proportional to that of the melanocytes, and (2) the number of the indeterminate dendritic cells remained constant. A pair of flanking indeterminate dendritic cells which appeared to be divided daughter cells was incidentally found a week after the start of the experiment. Our results suggest that the indeterminate dendritic cell could be an undifferentiated cell which might give rise to either one of the other epidermal dendritic cell types