Contributions to the evolutionary study of the liver afferent veins

The extra- and intrahepatic venous afferent devices have been followed up in their evolution in all the classes of vertebrates and in man. There were studied 319 cases in 19 vertebrate species, in situ by the method of corrosion preparates with acid-resistant plastic materials or radiographies. The extraparenchymal afferent venous device shows an evolution characterized by the maintenance and improvement of the visceral hepatic venous system and by the gradual freeing of somatic parietal afferences, substantiating new anatomical notions like "liver visceralization", "hepatic parietal territories" and allowed the ascertainment of an evolutionary phyletic line of the liver based on the progressive diminution of the hepatic parietal territory. The basic characteristic type of intrahepatic distribution of the portal vein was sketched beginning with the testudine reptiles and was maintained including man. The liver segmentary angioarchitecture appeared already in birds. These findings allowed the homologation of the cleaved liver with the unitary liver of mammals and man as well as the homologation of the hepatic organ of mammals, birds and of some reptiles, and the understanding of the emergence variation of the portal vein ventrocranialis dexter.