The Structure of the Nephrons of the Kidneys of Premature Infants With Extremely and Very Low Body Weight, Born as a Result of Very Early Preterm Birth at the Post-Conceptual Age

Abstract

It was found that children born as a result of early preterm birth are characterized by nephronogenesis, characterized by atypical increase in size, variability of nephron components, and recapitulation of mesonephronogenesis. The kidneys of premature infants with extremely low body weight are characterized by a peculiar structure, which is manifested in a reduced number of nephrons at birth, a pronounced glomerular-tubular imbalance – the structural and functional predominance of the glomerular component over the tubular part of the nephron. The concept of a new period of human ontogenesis is proposed – metanatal, which is understood as the period of life of a person born with extremely low and very low body weight as a result of early and early preterm birth, during 22–36 weeks of postconceptual age. The concept is based on the uniqueness of the structure-forming processes that occur in organs, which can not be evaluated as either embryo-fetal or postnatal ontogenesis processes after physiological delivery of 37–40 weeks of gestational age. Probably, these processes should be designated as postconceptual morphogenesis.