Development of the human infrahepatic inferior caval and azygos venous systems

Abstract

Differences in opinion regarding the development of the infrahepatic inferior caval and azygos venous systems in mammals centre on the contributions of 'caudal cardinal', 'subcardinal', 'supracardinal', 'medial and lateral sympathetic line' and 'sacrocardinal' veins. The disagreements appear to arise from the use of topographical position rather than developmental origin as criterion to define separate venous systems. We reinvestigated the issue in a closely spaced series of human embryos between 4 and 10 weeks of development. Structures were visualized with the Amira â reconstruction and Cinema4D â remodelling software. The vertebral level and neighbouring structures were used as topographic landmarks. The main results were that the caudal cardinal veins extended caudally from the common cardinal vein between CS11 and CS15, followed by the development of the subcardinal veins as a plexus sprouting ventrally from the caudal cardinal veins. The caudal cardinal veins adapted their course from lateral to medial relative to the laterally expanding lungs, adrenal glands, definitive kidneys, sympathetic trunk and umbilical arteries between CS15 and CS18, and then became interrupted in the part overlaying the regressing mesonephroi (Th12-L3). The caudal part of the left caudal cardinal vein then also regressed. The infrarenal part of the inferior caval vein originated from the right caudal cardinal vein, while the renal part originated from subcardinal veins. The azygos veins developed from the remaining cranial part of the caudal cardinal veins. Our data show that all parts of the inferior caval and azygos venous systems developed directly from the caudal cardinal veins or from a plexus sprouting from these veins.

The development of the cloaca in the human embryo

“…The black line shows the position of the aortic bifurcation (b; Hikspoors et al. ) or the temporal changes in greatest length of the embryo (divided by 10; C–F; O'Rahilly & Müller, ). Panel (B) shows that the entrance of the Wolffian duct into the cloaca/urogenital sinus (dotted red line; R 2 : 0.31) remained associated with segment 31–32 (S3–S4), whereas the tip of the urorectal septum (drawn red line; R 2 : 0.87) moved caudally to the level of the last coccygeal vertebra.…”

Left Retrocaval Ureter around the Ipsilateral Limb of a Double Caudal Vena Cava in a Cat

“…This model, which is applied in both human and veterinary embryology, states that the right-sided counterparts of three pairs of embryonic veins (i.e. the supracardinal, subcardinal and caudal cardinal veins) form the abdominal part of the caudal vena cava by means of fusion, anastomosis and asymmetric vascular degeneration during prenatal life (Huntington and McClure, 1920;Butler, 1927;Cornillie and Simoens, 2005;Cornillie et al, 2006;Hyttel, 2010;Sadler, 2012).However, a recent study revisiting the development of the inferior vena cava and vena azygos by means of three-dimensional reconstructions of human embryos (Hikspoors et al, 2015) has revealed various inaccuracies in the supracardinal system of Huntington and McClure (1920). All dorsal veins, formerly indicated as the supracardinal veins, must be considered as actual segments of the caudal cardinal system, which gradually adopts a different topography due to allometric growth of surrounding organs and tissues.…”

“…However, a recent study revisiting the development of the inferior vena cava and vena azygos by means of three-dimensional reconstructions of human embryos (Hikspoors et al, 2015) has revealed various inaccuracies in the supracardinal system of Huntington and McClure (1920). All dorsal veins, formerly indicated as the supracardinal veins, must be considered as actual segments of the caudal cardinal system, which gradually adopts a different topography due to allometric growth of surrounding organs and tissues.…”

“…Ventral schematic views of a human embryo (L, left side; R, right side) showing the development of the caudal vena cava (afterHikspoors et al, 2015). First (left image), a vascular ring around each kidney and ureter is formed by the caudal cardinal venous segments (1: I and IV) that drain into the subcardinal anastomosis (a and b) at the craniomedial poles of the kidneys (2), the infrarenal segments of the subcardinal veins (3: II and III) that collect (c and d) and interconnect (e) the left and right common iliac veins, and tributaries of both venous systems.…”

“…At a certain point during development, the caudal cardinal venous segments draining into the subcardinal anastomosis at the craniomedial poles of the kidneys, the infrarenal segments of the subcardinal veins collecting and interconnecting the left and right common iliac veins, and tributaries of both venous systems, form a vascular ring around the ipsilateral kidney and ureter (Cornillie and Simoens, 2005;Hikspoors et al, 2015). This complex venous configuration evolves from a bilateral symmetrical system to a single, right-sided vein, in a process during which the leftsided counterparts of all aforementioned veins gradually disappear (Cornillie and Simoens, 2005) (Fig.…”