The effect of sodium hydroxide and hydrochloric acid on pig dermis. A light microscopic study.

In order to compare the dermal changes after exposure to direct current (d.c.) with changes after influence of acid and base influence, the skin of fully anaesthetized Danish Landrace pigs were exposed to acid and basic solutions. Biopsies were obtained immediately after and up to day 7 after the injury. Collagen fibres with increased affinity for eosin and irregular cross-striation in polarized light together with shrunken cells with dark stained nuclei were found just beneath the epidermis immediately after application of 1 N HCl. Immediately after exposure to 1 N NaOH dispersed collagen fibres showed increased eosinophilia and a fine densely spaced cross-striation in polarized light and vesicular nuclei were present within dermal cells. During the following days a narrow demarcation zone of neutrophilic granulocytes separated the zone containing abnormal collagen fibres from normal tissue below. Calcified collagen fibres were not observed and no other abnormal histochemical reactions were present. It is concluded that the morphology of acid induced lesions and base induced lesions shows resemblance to the morphology of anode and cathode lesions, respectively, but not to heat lesions. The reason for not finding depositions of calcium salts on collagen fibres in skin exposed to basic solutions could be a non-optimal pH in the tissue or that other electrochemical processes than shift in pH are necessary for the calcification process.