[Participation of the myocardium in the formation of the pulmonary vein wall of small mammals (a quantitative study)].

The thickness of the layer of cardiac muscle cells in the wall of the pulmonary veins was studied and quantitatively evaluated. The thickness of the intrapulmonary myocardial layer in the tunica adventitia of the venous wall depends on the body mass of the animal. This relation can be expressed by a hyperbola. In animals with the body mass of approximately 50-400 g, the venous pulmonary myocardium can be observed only as a continuous coat in the intrapulmonary veins up to the diameter of 170 mcm. In animals with the body mass of approximately 3--50 g, the myocardial layer reaches all branches of the pulmonary veins up to the diameter of 50--100 mcm.