Figure 9. Micrographs showing immunohistochemical staining for PACAP-LI in the guinea pig.
A, inferior mesenteric ganglion; B, intermesenteric nerve trunk; C, hypogastric nerve trunk; D, lumbar colonic nerve trunk; E–G, myenteric ganglia of the distal colon; H, inferior splanchnic nerves; and I, L2 dorsal root ganglion. Note the varicose appearance of PACAP-LI in the IMG (panel A). No cell bodies containing PACAP-LI were found in the IMG. In the lumbar colonic, hypogastric and intermesenteric nerves (panels B–D) there were numerous nerve fibres containing PACAP-LI. Only a few PACAP-LI nerve fibres were found in the inferior splanchnic nerves (panel H). A small number of cell bodies with PACAP-LI were found in the dorsal root ganglion (panel I). In the myenteric plexus of the colon (panel E), there was a dense network of nerve fibres containing PACAP-LI and occasional cell bodies of myenteric neurones also were stained. The shape-based classification of these neurones was unclear because of the dense network of intensely stained nerve fibres passing in the vicinity of the ganglion neurones. However, some of the neurones resembled Dogiel type I neurones having a single long axon and a few short dendrites (panel F) and some resembled Dogiel type II neurones having a smooth cell body and several long processes (panel G). The IMG, DRG and nerves were frozen sections (15 μm thick) and the myenteric plexus preparations were whole-mounts. Scale bars are 50 μm.