Functional Development of the Nephron

Within the first year of life the glomerular filtration rate increases dramatically due to modifications in the existing complement of glomeruli. During the formation of urine, the glomerular ultrafiltrate undergoes sequential transport processes in the 14 distinct segments of the renal tubule that gradually convert the ultrafiltrate into the final urine. Taken together with changes in the tubular transport of solutes, the growing infant is maintained in a positive balance for many nutrients. Infants born before 34 weeks have ongoing nephrogenesis and consequently, preterm kidneys are more susceptible to long-term injury. In this section, we provide an overview of how the different components of the fetal nephron adapt to the extrauterine environment and highlight the mechanisms by which the neonatal kidney maintains fluid and electrolyte balance.