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Vagal afferent innervation of the atria of the rat heart reconstructed with confocal microscopy
Author(s) -
Cheng Zixi,
Powley Terry L.,
Schwaber James S.,
Doyle III Francis J.
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19970428)381:1<1::aid-cne1>3.0.co;2-5
Subject(s) - nodose ganglion , plexus , endocardium , anatomy , biology , nerve plexus , vagus nerve , confocal , confocal microscopy , free nerve ending , afferent , autonomic ganglion , atrium (architecture) , connective tissue , neuroscience , medicine , microbiology and biotechnology , genetics , geometry , mathematics , stimulation , atrial fibrillation
We have used confocal microscopy to analyze the vagal afferent innervation of the rat heart. Afferents were labeled by injecting 1,1'‐dioleyl‐3,3,3',3'‐tetramethylindocarbocyanine methanesulfonate (DiI) into the nodose ganglia of animals with prior supranodose de‐efferentations, autonomic ganglia were stained with Fluoro‐gold, and tissues were examined in whole mounts. Distinctively different fiber specializations were observed in the epi‐, myo‐, and endocardium: Afferents to the epicardium formed complexes associated with cardiac ganglia. These ganglia consisted of four major ganglionated plexuses, two on each atrium, at junctions of the major vessels with the atria. Ganglionic locations and sizes (left > right) were consistent across animals. In addition to principal neurons (PNs), significant numbers of small intensely fluorescent (SIF) cells were located in each of these plexuses, and vagal afferents provided dense pericellular varicose endings around the SIF cells in each ganglionic plexus, with few if any terminations on PNs. In the myocardium, vagal afferents formed close contacts with cardiac muscles, including conduction fibers. In the endocardium, vagal fibers formed “flower‐spray” and “end‐net” terminals in connective tissue. With three‐dimensional reconstruction of confocal optical sections, a novel polymorphism was seen: Some fibers had one or more collaterals ending as endocardial flower sprays and other collaterals ending as myocardial intramuscular endings. Some unipolar or pseudounipolar neurons within each cardiac ganglionic plexus were retrogradely labeled from the nodose ganglia. In conclusion, vagal afferents form a heterogeneity of differentiated endings in the heart, including structured elements which may mediate chemoreceptor function, stretch reception, and local cardiac reflexes. J. Comp. Neurol. 381:1‐17, 1997. © 1997 Wiley‐Liss, Inc.