Representative fluorescence photomicrographs of L4 DRG neurons. The scale bars are 200 mm. (A) FG-labeled DRG neurons, (B) CGRP-ir DRG neurons, and (C) IB4-binding DRG neurons. All photomicrographs are from the same section. Arrows in A and B indicate FG-labeled CGRP-ir DRG neurons. Arrowheads in A and C indicate FG-labeled IB4-binding DRG neurons. FG-labeled DRG neurons were observed at all levels. (D) merged image acquired from 3(B) and 3(C). There were no overlaps between the CGRP-ir and IB4-binding DRG neurons (E) The average numbers of the FG-labeled L4 DRG neurons. The numbers did not significantly change between each time point. (F) Average proportion of FG-labeled CGRP-ir or IB4-binding DRG neurons. CGRP-ir or IB4-binding DRG neurons were observed at every level of DRG without significant deviation in each experimental group. The numbers of ipsilateral FG-labeled CGRP-ir DRG neurons were significantly increased after 7 days after the intraarticular injection, whereas the contralateral DRG showed no significant change in the expression of CGRP. The proportion of IB4-binding DRG neurons showed no significant differences among the groups.