3.25 in. x 4 in. Lantern Slides, Original Magnification: x12,100, and The use of osmium tetroxide as a fixative for electron microscopy was first described by Dr. Palade at the Rockefeller. Another major advance in fixation for electron microscopy was done at Yale by David Sabatini who described the use of glutaraldehyde which not only preserved ultrastructure, but enzymatic activities which opened up the possibility of EM localization of enzymatic function in cells. Dr. Sabatini later joined the laboratory of Dr. Palade at the Rockefeller where he carried out his PhD studies on ribosomes and their relationship to the ER membrane during synthesis of exportable proteins.