Letter from Howard Walter Florey to Janet A Jenkinson, Zoology Department, University College, Cardiff Is sorry there are no reprints left of paper on endothelial cells - possible that results differ greatly according to the animal tissues - use standard araldite embedding - could stain specimens whole in watery uranyl acetate - might try glutaraldehyde fixation, followed by treatment with O5o4 and then uranyl acetate - avoid Pb Cit as can form fine particles difficult to distinguish from ferritin. 27 June 1967