A study of the effect of acid and alkali on melanogenesis in the skin

Summary

• 1. Twenty per cent acetic acid and a four per cent solution of sodium hydroxide were applied to the anterior abdominal wall skin of two separate groups of male guinea-pigs for five days/week/4 weeks. Each group consisted of six pure black and six pure red animals.

• 2. The acetic acid caused a reduction in the depth of colour of the melanin within the melanocyte cell bodies and in five of the animals a reduction in the amount of intra-cellular melanin. In seven of the animals, the length and complexity of the dendritic processes were increased. The majority of the animals showed no change in the appearances of the free melanin. A significant rise in the melanocyte count occurred.

• 3. The sodium hydroxide solution produced an increase in the amount of free melanin. The amount of melanin present within the melanocytes showed a tendency to become reduced. In some of the specimens areas of total epidermal destruction had occurred and in these regions dermal melanophores loaded with melanin were clearly seen. A significant rise in the melanocyte count took place.