Figure 4. (A) Electron microscopy on the preparation containing rPrP demonstrated circular membrane profiles of unconfirmed origins in addition to electron dense amorphous material. (B and C) After inoculation into intestinal loops, electron dense amorphous material and circular structures were observed non-cell-associated in the lacteals (arrows) (B) and in the cytoplasm of a mononuclear cell (delineated) (C). Immunogold labeling showed rPrP labeling of inconspicuous electron dense amorphous aggregates (arrows) and on membranes of circular profiles in a lacteal (D) and in the cytoplasm of a mononuclear cell (delineated) (E). Scale bars, 1 µm. (l) lacteal, (lp) lamina propria, (e) endothelial cell, (c) cytoplasm, (n) nucleus.