[The portal system (vena portae). Embryology and morphology (author's transl)]

The embryology and anatomy of the portal system are reviewed in the light of data reported in the published literature. A detailed description of the mode of formation of the portal vein and its branches up to the 52nd day of intrauterine life is given, this being the period when embryonic features are comparable to those in adults. Dimensions and physiological variations during growth are discussed, though it is regrettable that few studies have been concerned with this aspect. Portal system afferent vessels are then described and several statistics cited, this providing an explanation for the different modes of origin of the main portal vessel, and the limits of the regions not receiving collaterals. These anatomical zones, isolated in this manner, represent elective zones for surgical approach and for anastomotic procedures.