[Morphofunctional study of the cava-hepatic venous transition in humans].

Using mesoscopic techniques, the authors observed that fibrous muscular bundles were distributed in three layers, from the external to the intima, in the cava-hepatic venous transition zone; these bundles start with a helical course, and bend progressively towards their outlet. Regarding the collagen component, two kinds of fibre bundles were observed: 1) as longitudinal strips, two for each vein that join in an arched form close to the outlet; 2) bundles running in the same direction as muscular bundles. The elastic tissue appears as a component of the myoelastic tendons or as independent bundles. The latter follow the direction of the muscular fibres, but show a decreasing amount when they approach the transition zone. At this point, however, the myoelastic tendons grow thicker.