ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Electron microscopy of the turtle sinus venosus shows an unusual neuron soma which is immediately surrounded by myocardial cells so as to form a somato-muscular complex. Studies of 36 sections cut through this neuron soma indicate that 27.4% of the somal surface studied is directly covered by cardiac muscle cells without any intervening basal lamina. Similarly, 18.8% of the somal surface studied is in contact with unmyelinated axons which at places make typical axosomatic synapses. A coupling of peripheral cisterns of the sarcoplasmic reticulum and the sarcolemma exists at the somato-muscular contiguity as well as at the border between cardiac muscle cells. It is suggested that neural influences upon the pacemaking activity of the turtle heart sinus can well be exerted through the somato-muscular pathway. Additionally, an axon which is presynaptic to the neuron soma has been observed to be simultaneously in a synaptic relation with a cardiac muscle cell; a remarkable deviation from the classical picture of the efferent nervous outflow to the heart.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091790409
