[Structural organization of the wall of the inferior vena cava in rats].

Structural organization of the wall in the posterior vena cava has been studied with light optic (neurohistological and neurohictochemical techniques including) and electron microscopical methods in mature and 1-month-old rats. According to its structure, the vascular wall in question can be divided into 3 parts. Two of them are situated in the thoracic cavity, the first occupying a half of the thoracic part of the vein, is surrounded with cardiomyocytes, and in the second part the wall consists of endotheliocytes, fibroblasts, collagenous and elastic fibres. The third part of the vein is situated in the abdominal cavity; together with endotheliocytes, internal elastic membranes and collagenous fibres there is a great number of adrenergic neural fibres, a well developed middle membrane is presented by smooth muscle tissue; there is also a layer of "veil-like" fibroblasts. All the elements of the wall are connected with each other and function as a single whole. Endothelial-muscular, muscular-muscular and neuro-muscular connections seem to be of a special functional importance. Structural differences in the venous parts mentioned above appear to be connected with their functional pecularities. Structural differentiation in the young rat venous wall and myocytes coinsides with the differentiation of adrenergic nerve structures.