Morphological Assessment of Kidney Cortical Substance Development in Childhood

Abstract

One of the factors for arterial hypertension development is an increase in the activity of the renin-angiotensin-aldosterone system. It is supposed to be relevant to study the structure of subcortical and perimedullary nephrons in order to identify their morphofunctional characteristics in postnatal ontogenesis.
 The aim of the study was to investigate the age-related characteristics of the renal cortex structure in children of different age groups.
 Materials and Methods. The study was performed on the autopsy renal material obtained from children without any vascular and renoparenchymal diseases, who died at the age of 2 months – 10 years. Six age groups were identified: those who died at the age of 2–4 months, 6–9 months, 10–12 months, 3 years, 6 years, and 10 years. Paraffin microscope slides were prepared according to a standard method and stained with hematoxylin and eosin. The authors determined the number of subcortical and perimedullary renal corpuscles, cortical and perimedullary nephron area, glomeruli area of subcortical and perimedullary nephrons and their average capsule area using the Levenhuk morphometric program.
 Results. In postnatal ontogenesis, uneven maturation of the cortical renal substance is observed. Initially, the nephrons of the subcapsular zone develop faster, with predominant growth of convoluted tubules. Nephron number in the perimedullary zone is lower than in the subcortical one. Active tubule and stroma growth is observed since the age of 3. By the age of 10, the number of subcortical and perimedullary nephrons becomes the same and corresponds to the kidney structure in adults. In ontogenesis, the corpuscles and vascular glomeruli of the pericerebral nephrons are larger than those of the subcapsular ones. However, the urinary space is wider in the subcapsular nephrons, which indicates their earlier involvement in the urination process. A significant development of the vascular glomeruli of the perimedullary nephrons indicates their predominant involvement in the processes of blood pressure regulation through renin synthesis.