Organogenesis of the venous structures of the human liver: A hemodynamic theory

Abstract

Reconstruction of human embryonic livers (Streeter's developmental horizons XVI, XIX and XX) showed that hepatic segmentation arises between the 35th and 45th day of intrauterine life and that the vena umbilicalis sinistra plays an important role in this developmental phenomenon. Conversely, the results of this study demonstrated the regressive and non functional nature of the vena umbilicalis dextra and vitelline vessels. Furthermore, our observations allowed to identify the embryonic period during which umbilical blood flow begins to invest the mass of hepatic cells and runs about the sinusoids. The flow pattern described in this report induces special fluid currents which are reflected by a progressive increase in the variability of the venous structures lying more and more distally to the point of entry of the vena umbilicalis sinistra in the liver. These hemodynamic phenomena could thus account for the constancy of the left part and the variability of the right part of the liver, as well as the variability of the site of origin of the right paramedian vein with respect to the bifurcation of the vena portae.