PECULIARITIES OF SOURCES OF RUDIMENTS AND MORPHOGENESIS OF THE PELVICALYCEAL SYSTEM OF THE KIDNEY IN EARLY PERIOD OF THE HUMAN PRENATAL ONTOGENESIS
Authors: Tsyhykalo O.V. , Andrushchak L.A. , Vladychenko K.A. , Galysh I.V. 
Published: November 2022

The aim of the study – to determine the peculiarities of the rudiments sources and thechronological sequence of topographical and anatomical transformations of the organsand structures of the human urinary system.Materials and methods. The material for the study was 14 series of consecutivehistological sections of specimens of human embryos and prefetuses (4.0-66.0 mm parietalcoccygeal length (PCL)) aged from 4th to 11th weeks of intrauterine development (IUD) A complex of modern methods of morphological research (anthropometry, morphometry,microscopy, 3D computer reconstruction, statistical analysis) were applied.The results. The first signs of mesonephric duct diverticula formation are determined inhuman embryos of the 5th week of the IUD (embryos 7.0-7.5 mm PCL). It is represented byan ampoule-like blind expansion of the diverticulum – the primary rudiment of the renalpelvis, which is surrounded by a condensed mesenchyme, that is the formation sourceof the renal parenchyma – a nephrogenic blastema. Starting from the embryos of themiddle of the 5th week of IUD, due to 3D computer reconstruction, the first topographicaland anatomical features of the primordia of the structures of the definitive kidney aredetermined. The rudiments of the renal pelvises – paired ampoule-like blind expansionsof the diverticulum of the mesonephric duct – are immersed in the metanephric blastema,which has the shape of a drop due to the upper narrowed end. Starting from the end of the6th week of IUD, there is a evagination of the wall of the blind end of the diverticulum (therudiment of the renal pelvis) in the cranial and caudal directions, i.e., the rudiments ofmajor calyces appears. The rudiments of the minor cups is formed by the evagination ofthe wall of the major calices and appears in prefetuses at the beginning of the 7th week ofIUD. Age-related topographical and anatomical changes of the kidneys were also traced.Conclusions. 1. On the specimens of embryos 4.7-5.5 mm PCL (4th week of IUD),mesodermal sources of rudiments of structures and organs of the genitourinary system,which originate from the paired genitourinary crest, are determined. At the border of thedorsal and ventral parts of the mesoderm, in the intermediate mesoderm, the source of theurinary tubules is carried out, which form the nephrogenic cord – the only source of layingof all three generations of the kidney. At the end of the 4th week of IUD, an evaginationappears on both sides from the dorsal wall of the excretory duct of the mesonephros in itscaudal part, which is the rudiment of the epithelial lining of the ureter and renal pelvis.2. The rudiment of the renal pelvis is observed for the first time in the 5th week of IUD(embryos 7.0-7.5 mm PCL), major cups – at the end of the 6th week of VUR (embryos12.0-13.5 mm TKD), small calices – at the beginning of the 7th week of IUD (prefetuses14.0-15.0 mm PCL). 3. In the process of intrauterine development, the kidneys move fromtheir original location in the pelvis, where the source of their blood supply is the commoniliac artery, cranial to the primordia of the adrenal glands, giving their own vessels to theaorta, which become renal arteries.