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An electron microscopic study on the innervation of the trout heart
Author(s) -
Yamauchi Akio,
Burnstock Geoffrey
Publication year - 1968
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/cne.901320406
Subject(s) - myofibril , biology , anatomy , ventricle , axon , myocyte , cardiac muscle , auricle , ganglion , trout , microbiology and biotechnology , fish <actinopterygii> , medicine , endocrinology , fishery
The neuromuscular inter‐relationship was investigated in three regions of the trout heart: the sinoauricular junction, the auricle and the ventricle. The innervation of the sinoauricular tissue was unusually dense; in one plane of section, the number of axons less than 200Å apart from cardiac muscle cells was approximately equal to the total number of muscle cells. Some muscle cells had up to eight close axon contacts. It is suggested that every muscle cell in this region of the fish heart has at least one and probably many more individual neuromuscular contacts. Many ganglion cells, some with presynaptic terminal were observed in the sinoauricular region. Multivesicular bodies were commonly seen in the cytoplasm. The innervation of the ventricle near the apex was very sparse and that of the auricle appeared to be intermediate between the two extremes. The ventricular muscle cells were somewhat larger and contained a higher area of myofibrils than those in the auricle and the sinoauricular tissue. M‐lines in the myofibrils were demonstrated in the cardiac muscle of the trout. Intraaxonal vesicles were mostly agranular. However, in about 9.5% of the 1472 axon profiles examined, a number of small (500–700Å) and large (∼800Å) granular vesicles were also present, which suggests that, in contrast to the general view, there are some nerves containing catecholamines supplying the fish heart. It is likely that the sinoauricular region in the fish heart is homologous to the smus node in avian and mammalian hearts.