I was wondering if someone can compare the functionality of vitamin A, Bx (x means numbers, such as 1, 2, 3, ...), C, D, E, K in the skin? They are used in cosmetics but what is their actual effect? ...
As in the subject line, what percentage of capillaries in a human (expressed in terms of total length, I suppose) are located in the skin, as opposed to internal organs? Google scholar has not turned ...