Regional histomorphometry of the hepatic inferior vena cava; a possible sphincteric mechanism / Histomorfometría regional de la vena cava inferior hepática; un posible mecanismo de esfínter

This study was aimed at identifying the changes in diameter and structural composition of the Hepatic Inferior Vena Cava in its infrahepatic, intrahepatic and suprahepatic portions. Eighty adult liver specimens from the Chiromo and Nairobi City mortuaries were used for morphometry, while twenty of them were processed for light microscopy. A constriction was noted in the mid-portion of the HIVC, while structurally; the intrahepatic portion had thicker fibromuscular adventitia. It is plausible that these are sphincteric apparatus to prevent backflow of blood in the Hepatic Inferior Vena Cava.

Este estudio tiene por objetivo identificar los cambios en el diámetro y la composición estructural de la vena cava inferior hepática en sus porciones infrahepática, intrahepática y suprahepática. Ochenta hígados de especímenes adultos de los depósitos de cadáveres de la ciudad de Nairobi y Chiromo fueron usadas para morfometría, mientras que veinte de ellos fueron procesados para microscopía de luz. Se observó una constricción en el medio de la HIVC, mientras que estructuralmente, la porción intrahepática había una gruesa adventicia fibromuscular. Es posible que este sea un aparato esfinteriano para evitar el reflujo de sangre en la vena cava inferior hepática.

Topographical relationships among the portal branchesand the hepatic tributaries in the left lateral division or the liver of brazilian individuals

The left lateral division or left anatomical lobe of the liver is subdivided into posterior lateral or S2 and the anteriorlateral or S3 segments. Because this lobe is widely used in hepatic transplantation, the ramifications of the portal veinand of the hepatic veins have been extensively studied. The aim of this study was to investigate the frequency ofcases in which it is possible to delimit the S2 and S3 hepatic segments. Forty livers from Brazilian subjects ofEuropean and African descent were fixed in neutral formalin solution and dissected. In segment S2, there was alwaysa portal branch located dorsally to the left hepatic tributary. In segment S3, there were three types of interdigitationsdistributed among two portal branches and two hepatic tributaries. In type A (26/40 cases, 65%), the tributariescrossed the dorsal portal branch posteriorly. In subtype A1 (19/26 cases), the tributaries pinched the ventral branch,and in subtype A2 (7/26 cases), they crossed the ventral branch posteriorly. In type B (11/40 cases, 27.5%), the twotributaries pinched the dorsal portal branch, with both pinching the ventral portal branch in subtype B1 (7/11 cases)but only the ventral tributary crossing the latter branch in subtype B2 (4/11 cases). In type C (3/40 cases, 7.5%), theventral and dorsal tributaries crossed the dorsal portal branch anteriorly, with both vessels also crossing the ventralportal branch anteriorly in subtype C1 (2 cases) and only the ventral tributary crossing this branch in C2 (1 case). Inall cases, it was possible to differentiate S2 from S3, even when in type C cases there was no hepatic tributaryseparating them. Moreover, in 23/40 cases (57.5%) there was a fissural umbilical vein greater than 5 mm in diameterand, in 5/23 cases this vein superficially crossed the portal branch destined to segment S3.