Immunohistochemistry for PrP^Sc.

<p>Scrapie inoculated sheep. Immunolabelling was most abundant in the light zone of the germinal centre (GC) but a few scattered strongly labelled cells were also present in the dark zone near the outer rim of the lymphoid nodule delineated by spindle-shaped cells (arrowheads, also in inset). In the marginal zone (MZ), an abundant finely granular labelling was prominent and in the PALS (P) a few medium-sized granules (arrow), often close to the arteriole (a), were labelled. RP: red pulp. Bar, 100 µm. Nuclei were stained with haematoxylin.</p

Immunohistochemistry, double labelling for PrP^Sc (<i>brown colour</i>) and nerves (<i>PGP, red colour</i>).

<p>Scrapie inoculated sheep. A, B. In the germinal centres (GC), a few nerve fibres were present in close association with cells strongly immunolabelled for PrP^Sc (A; inset). In some areas, the lymphoid nodules were separated from the PALS by a narrow rim of spindle-shaped cells (A, B; arrowheads) with PrP^Sc labelling mostly confined to the nodule side of the rim. In the PALS, nerves were most abundant around the arteriole (a), sometimes with PrP^Sc-labelled granules close to the nerve fibres (A; arrow). Among the lymphoid cells of the PALS, a few nerve fibres and small granules labelled for PrP^Sc were generally not co-localised. In the red pulp (A; RP) and the marginal zone (B; MZ), longitudinally and cross-sectioned small nerve fibres (B; white arrows) were abundant. C. High power view of B, showing the PALS-germinal centre transition (arrowheads), PGP labelled nerve fibres (white arrows) and PrP^Sc (black arrows). D. In the marginal zone, the nerve fibres (white arrow) were often close to numerous small granules labelled for PrP^Sc (black arrows). Bars, 100 µm (A, B), 10 µm (C, D). Nuclei were stained with haematoxylin.</p

PrP mRNA expression in splenic compartments.

<p>PrP mRNA expression levels in compartments of spleen of five VRQ/VRQ lambs after oral inoculation with scrapie (black columns) and five control lambs (gray columns). The y axis represents mRNA levels relative to GAPDH expression obtained by real-time RT-PCR analysis. Error bars represent standard deviation. There was no significant difference in PrP mRNA levels between the scrapie-inoculated and control animals. The level of PrP mRNA expression in the red pulp (RP) was significantly higher than in all other tissue compartments, namely the periarterial lymphatic sheaths (PALS), lymphoid nodules (LN), marginal zone (MZ) and trabeculae (TR).</p