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. 2014 Nov 10;9(11):e112466. doi: 10.1371/journal.pone.0112466

Figure 9. Anterograde labeling from lumbosacral DRG in vivo reveals two distinct types of spinal afferent nerve ending identified in the submucosa.

Figure 9

A, shows a “branching-type” spinal afferent nerve ending in the submucosa. This ending ramifies extensively with many branching varicose axonal processes that align preferentially in the rostral-caudal axis, within the submucosa. The region indicated by the arrow in panel A is shown on expanded scale in panel B. The nerve endings indicated by the arrow in panel B are not CGRP positive (compare with arrow in panel C). Panel C shows CGRP immunoreactivity of the region shown in panel B. The arrow shows a lack of CGRP immunoreactivity of the ending indicated by the arrow in panel B. Panel D, shows a superimposed image of panels B & C. Panel E, shows a “complex-type” spinal afferent ending in the submucosa at the same level as the base of the Crypts of Lieberkhun. This complex type ending arises from a single spinal afferent axon and then ramifies into a complex structure with multiple varicose axons that branch in no apparent preferential orientation. The arrow in panel E indicates a varicose axonal ending that is not CGRP positive (compare with arrow at the same region in panel F). F, shows CGRP immunoreactivity of the same region shown in panel D. The arrow in panel F shows a lack of CGRP immunoreactivity of the ending in panel E. G, shows a superimposed image of E & F. It is clear that this complex-type spinal afferent ending is not CGRP immunoreactive - compare arrows in panels E, F & G.