<b>DISTRIBUTION OF -SH AND S-S IN EPIDERMIS AND ECCRINE GLANDS: COMPARISON OF THE FINDINGS BASED ON THE ROUTINE AND <i>N</i>-(7-DIMETHYLAMINO-4- METHYL-3-COUMARINYL)MALEIMIDE (DACM) </b><b>STAININGS </b>

Abstract

N-(7-Dimethylamino-4-methyl-3-coumarinyl)maleimide (DACM) staining is an excellent new histochemical method used to show the distribution of -SH groups and S-S linkages, by utilizing fresh frozen tissue sections. This study shows that deparaffinized skin sections are applicable to the DACM reaction and can be examined by hematoxylin-eosin and other stainings after fluorescent microscopy of the reaction. There are no differences in the distribution and intensity of the DACM reaction in -SH groups and S-S linkages between frozen and deparaffinized sections, although the incubation time in NEM (N-ethylmaleimide) solution to block -SH groups in tissue should be longer in deparaffinized sections than in frozen ones. The advantage of the deparaflinized sections is that they display very fine structures with the DACM reaction.Comparison of the findings by DACM staining to those by routine staining in a same skin section reveals that -SH groups are most strongly distributed and S-S linkages suddenly appear in the lowest part of the horny layer immediately above the granular layer of the epidermis. In eccrine glands, -SH groups are distributed moderately in the secretory cells and strongly in the myoepithelial cells, whereas S-S linkages are absent in these cellular components except for the keratinized duct cells and the basement membrane.The DACM staining combined with routine stainings using deparaffinized sections is very useful in knowing the accurate distribution of -SH groups and S-S linkages in tissue sections.