Fig. 4

Typical axial sections at the cervicothoracic junction after injection of fluorescent tracer into the spinal grey and white matter. a–e Grey matter injection. a RECA-1 and d SMA immunofluorescent staining of arterioles. Examples of grey matter arterioles are marked by arrow heads in a, d. Arterioles were present in greater numbers in the grey matter compared to white matter. b Fluorescent microspheres confirmed the Nanofil needle had traversed the grey matter. c, e Radial redistribution of tracer from the middle of the grey matter in all directions. f Axial section rostral to a grey matter injection site where a significant amount of tracer had spread into dorsal column. Note tracer fluorescence was mainly confined to the dorsal white matter column at this level. g After delivery into the white matter, AFO-647 tracer conformed to the shape of the lateral funiculus with limited spread into the grey matter. h In rostral sections in the same animal, tracer was confined to the white matter. Arrow heads demonstrating selective tracer deposition around arterioles. All fluorescent photomicrographs were taken at ×20 magnification