Sulphydryl and disulphide groups in normal and irradiated epidermis.

The distribution of sulphydryl (SH) and disulphide (SS) groups in normal and irradiated epidermis of newly-born rats was studied by microspectrophotometric quantitation of the Mercury-Orange reaction. In order to obtain information on (1) the total content of both groups within the different strata of the epithelium, and (2) the mean SH and SS concentration, which is an indicator of the density of these groups per unit of tissue. The content of both groups increased in relation to the extent of irradiated area, whereas there was a decrease in the mean concentration. The increase in content of SH and SS would lead to augmented production of keratin substance previously reported in irradiated epithelia, coincidentally with an acanthotic response. The decrease in concentration of SH and SS indicates a destruction of these groups at cellular level, which may be due to membrane alterations. The findings would explain an acceleration of the keratinizing process together with modifications, both in quality and in quantity, in the horny substance.