Figure 2.

Ultrastructural localization of PrP^C in the neuropil in hippocampal CA1 area. Labeling was performed using Fab D18 and protein A-gold (10 nm). A, Absence of PrP^C labeling in a Prnp^0/0 mouse. B, Stratum radiatum of a wt FVB mouse. Gold particles are localized on the axolemma (white arrows), myelin sheaths (white arrowheads), putative axon terminal membranes (black arrowheads), synaptic vesicles (black arrows), axonal transport vesicle (near asterisk), and synaptic specialization (double-headed arrow). Gold particles without arrows belong to processes, which are difficult to identify as being either dendritic or axonal. C, Stratum radiatum from a wt FVB mouse. As in B, gold particles can be found at the synaptic specialization (double-headed arrow) and on the membranes of the postsynaptic profile (arrowhead). D, Stratum oriens of a wt FVB mouse. Gold particles are localized on the dendritic shaft (white arrowheads), small processes (white arrows), and synaptic vesicles (black arrow). E, Stratum radiatum of a wt FVB mouse, longitudinal section of a dendrite. Gold particles are localized on the dendritic shaft (white arrowheads), membrane of a spine (black arrowhead), and small processes (white arrows). The particle inside the spine probably sits on the spinal apparatus, which is not clearly identifiable because of the tangential orientation. Relative distribution of the immunogold labels is provided in Table 1; B and D do not reflect quantitative information. ax, Myelinated axon; den, dendrite; m, mitochondria; sb, synaptic bouton; sp, spine. Scale bars, 200 nm.