Histochemical localization of oxidized glutathione-catalysing enzymes in human term placenta

This paper reports a new cytochemical affinity technique for detecting oxidized-glutathione-binding enzymes by light microscopy and for carrying out fine structural analyses by means of oxidized glutathione labelled with colloidal gold. Albumin-colloidal gold particles were prepared. Oxidized glutathione, added to the solution, replaced albumin on the surface of the gold, thus forming a new histochemical reagent. In human placenta, oxidized-glutathione-catalysing activity was detected on the brush border of the placental villi, over the foldings of endothelial membranes, and in the ground substance of connective tissue in the villous core. Every process of the cell membrane demonstrated enhanced oxidized-glutathione-catalysing activity. This new reagent is a unique example of a low-molecular-weight compound labelled with colloidal gold, and it permits direct measurement of oxidized-glutathione-binding activity in tissue sections.