[The innervation of the conducting and working myocytes in the sinoatrial area of the canine heart (a quantitative study)-].

Quantitative electron microscopic study of the innervation of different types of specialized sinus node conducting myocytes and of working myocytes in the perinodal myocardium of the right atrium was carried out in intact dogs. Differences were found in diameters of unmyelinated nervous fibers and their efferent terminals and distances between them and sarcolemmas of myocytes of the types studied. It was demonstrated that qualitatively different synaptic vesicles in the efferent terminals near the nodal and working myocytes are encountered with different frequency. Similar parameters of innervation of the nodal and working myocytes in sinauricular region of the heart were compared in intact dog and rat.