Blood supply formation of the upper urinary tract in the prenatal period of human ontogenesis

Abstract

Objective — to clarify peculiarities of blood supply of the upper urinary tract in the fetal period of human ontogenesis.Material and methods. The study was conducted on 58 specimens of human fetuses 81,0–375,0 mm of the parietal-coccygeal length (PCL) (4–10th months of the intrauterine development). A complex of morphological examinations was applied including anthropometry, morphometry, vascular injection followed by radiography and dissection, microscopy, graphic reconstruction and statistical analysis.Results. Definitive topography of the blood vessels of the upper urinary tract is established at the beginning of the fetal period. The abdominal part of the ureter is supplied by the ureteric branches of the testicular (ovarian) artery, the branches of the renal and capsular arteries. In the proximal ureter their anastomosis is determined. Variations of blood supply to the abdominal part of the ureter are arterial branches from the aorta and common glomerular arteries. At the end of the fetal period of human ontogenesis the shape of the ureter’s arteries becomes twisty that coinciding with the accelerated growth rate of their length and the slower increase of the ureter’s length. The paraureteral tissue in the surrounding layers of the retroperitoneal fascia, especially it is more prominent behind the abdominal part of the ureter, is clearly defined in the fetal period of the development. Venous outflow from the abdominal part of the ureter occurs proximally in the kidney, distally — in the ureter, capsular, testicular (ovarian) veins. An arcuate vein is clearly defined on the lateral surface of the pelvic-ureteral segment. It probably plays the role of a venous circular circle between different ways of blood outflow from the abdominal part of the ureter.Conclusions. 1. Blood supply of the abdominal segment of ureter in fetuses is ensured by the branches of the ureteral, testicular (ovarian) and renal capsular arteries. 2. The parapelvic ureteral segment is characterized by the availability of the three intraparietal venous plexuses located in the submucous, muscular and adventitial tunics anastomosing between themselves due to permeable veins. 3. A venous collector of the abdominal segment of ureter is arcuate vein located on its lateral wall. Venous outflow occurs in two directions: cranially — in the capsular and renal veins, caudal — in the capsular, ureteral and testicular (ovarian) veins. 4. 4–5 months of the development are critical periods of the abdominal ureter. This is a time for possible occurrence of congenital defect variants of blood vessels syntopia.