COMPARISON OF LR WHITE AND UNICRYL AS EMBEDDING MEDIA FOR LIGHT AND ELECTRON IMMUNOMICROSCOPY OF CHROMAFFIN CELLS

LR White and Unicryl are members of the same family of acrylic embeddi ng resins and are very suitable for ''on grid'' postembedding immunogo ld labeling, We studied the ultrastructure of LR White- and Unicryl-em bedded cultured chromaffin cells and the immunolocalization of three c hromaffin cell proteins, the enzymes dopamine-P-hydroxylase (DPH) and tyrosine hydroxylase (TH), and the membrane fusion and Ca2+ channel pr otein synexin (annexin VII). We report here that Unicryl is preferable to LR White as an embedding medium for electron microscopy when osmiu m tetroxide fixation is omitted, The basis for this distinction is bet ter ultrastructural preservation and improved immunodetection efficien cy.