MOG knockout mice display aberrant sprouting of TrkA- and CGRP-positive fibers. (A and B) Pain fiber tracts in spinal cords from wild type (WT; MOG^+/+) and MOG knockout (MOG^−/−) were analyzed by staining for TrkA (A) and CGRP (B). Aberrant sprouting of nociceptive axons and increased density of TrkA- and CGRP-positive fibers were observed in MOG^−/− compared with MOG^+/+ mice. (A) Spinal cords from wild-type (MOG^+/+) and MOG knockout (MOG^−/−) littermates were analyzed at 14 d postnatal. Spinal cord sections were matched and immunostained for MBP, MOG, and TrkA. (B) Magnified images of CGRP staining from the spinal cord images from 8 wk postnatal mice. (C) Spinal cords from MOG^+/+ and MOG^−/− littermates were analyzed at 2 wk postnatal. Sholl analyses and profiles were generated from spinal cord sections immunostained for CGRP. Bars, 100 µm. (D) The number of intersections were plotted against the distance from the center of the concentric circles. The data are represent the mean number of intersections from four spinal cords from the MOG^−/− mice and four spinal cords from MOG^+/+ littermate controls. (E) The total number of intersections was plotted for the wild-type and MOG^−/− mice. Student’s t test was used to compare the total number of intersections in wild-type versus MOG^−/− mice (*, P < 0.05). Error bars represent SEM.