Methods for studying the ductus venosus in animals

Abstract

The ductus venosus is a physiological vascular shunt to the umbilical and caudal vena cava in the fetus. The umbilical vein (vena umbilicalis) leaves the placenta, enters the fetus through the foramen umbilical, and goes to the liver hilum. It carries oxygenated and nutrient‐rich blood from the placenta to the fetus. Part of the blood enters the liver through the umbilical vein, through the shunt ‐ the ductus vein enters the central venous line ‐ the caudal vena cava. This mechanism of blood redistribution is necessary for feeding the fetal brain with blood that is more saturated with oxygen. Given the scarce data on the topography, shape, and morphometric parameters of the venous duct in animals, we set the goal of revealing the methods used for its postmortem study. For a complete and comprehensive study of the topography of the venous duct, it is necessary to use a set of anatomical methods: thin anatomical preparation, vasoradiography, production of corrosive preparations, and morphometry. When conducting vasoradiography, a mass for injection prepared according to the recipe was used as a radio‐opaque mass: 45% ‐ lead white, 45% ‐ gum turpentine, 10% ‐ medical gypsum powder (M.V. Shchipakina, A.V. Prusakova, D.S. Bylinskaya, S.A. Kuga, 2013). In the manufacture of corrosive preparations, self‐hardening dental plastic was used. It belongs to the acrylic group of cold curing plastics and consists of powder and solvent components. In both cases, the injection of these substances was carried out through the umbilical vein, without opening the abdominal cavity, by accessing through the umbilical cord. After introducing the X‐ray contrast mass, the objects of study were placed in a fixing solution (10% formalin solution) and left in it for up to 5 days. Subsequently, thin anatomical preparation and photography, as well as radiography, were performed. After introducing a plastic solution, the objects were placed in chambers with a temperature of +4°C for two days. Subsequently, corrosion treatment was carried out in an aqueous potassium hydroxide solution for 4 ‐ 5 days. The morphometry of the venous duct in the study of vaso‐radiographs was carried out in the RadiAnt computer program, in the study of a corrosive preparation ‐ using an electronic caliper (Stainless hardened). On vaso‐radiographs, the ductus venous is identified as a sizeable cone‐shaped vessel located in the area of the liver hilum. The ductus venosus is identified as a craniodorsal blood vessel that flows into the caudal vena cava on the casts of the vascular bed. The proposed methods for studying the ductus venosus make it possible to accurately anatomically describe the position, shape, and size of the ductus venosus in fetuses.