Ea. Fox et al., Vagal afferent innervation of smooth muscle in the stomach and duodenum ofthe mouse: Morphology and topography, J COMP NEUR, 428(3), 2000, pp. 558-576
Intraganglionic laminar endings (IGLEs) and intramuscular arrays (IMAs), th
e two putative mechanoreceptors that the vagus nerve supplies to the gastro
intestinal smooth muscle, have been characterized almost exclusively in the
rat. To provide normative inventories of these afferents for the mouse, th
e authors examined the endings in the stomach and small intestine of three
strains used as backgrounds for gene manipulations (i.e., C57, 129/SvJ, and
WBB6). Animals received nodose ganglion injections of wheat germ agglutini
n-horseradish peroxidase or dextran-tetramethylrhodamine conjugated to biot
in. The horseradish peroxidase tissue was processed with tetramethylbenzidi
ne and was used to map the distributions and densities of the two endings;
the dextran material was counterstained with c-Kit immunohistochemistry to
assess interactions between intramuscular arrays and interstitial cells of
Cajal. IGLEs and IMAs constituted the vagal innervation of mouse gastric an
d duodenal smooth muscle. IGLE morphology and distributions, with peak dens
ities in the corpus-antrum, were similar in the three strains of mice and c
omparable to those observed in rats. IMAs varied in complexity from region
to region but tended to Lt simpler (fewer telodendria) in mice than in rats
. IMAs were most concentrated in the forestomach and sphincters in mice, as
in rats, but the topographic distributions of the endings varied both betw
een strains of mice (subtly) and between species (more dramatically). IMAs
appeared to make appositions with both interstitial cells and smooth. muscl
e fibers. This survey should make it practical to assay the effects of gene
tic (e.g., knockout) and experimental (e.g., regeneration) manipulations af
fecting visceral afferents and their target tissues. (C) 2000 Wiley-Liss, I
nc.