Neuronal and vascular lesions in MyD88^−/− mice.

<p>Hematoxylin and eosin staining showing neutrophilic inflammation in perineurium and endoneurium of a perineal nerve from a MyD88^−/− mouse (arrows, A; 21 DPI). Abundant spirochetes are evident by immunohistochemistry within perineal nerves (arrow, B; 21 DPI and C; 42 DPI) and rarely skin (D; 21 DPI) despite the absence of other cutaneous lesions in MyD88^−/− mice. Spirochetes were never seen in nerves of WT mice (E; 42 DPI). In MyD88^−/− mice, spirochetes are present within the wall of a rectal vessel (arrow, F; 84 DPI) and the media of a perineal arteriole (arrows, G; 21 DPI). Bars = 20 µm in panels A,B,E and 10 µm in panels C,D,F.