Nascent nephrons during human embryonic development: Spatial distribution and relationship with urinary collecting system

摘要: The two major components of the metanephros, urinary collecting system (UCS) and nephron, have different developmental courses. Nephron numbers vary widely between species individuals are determined during fetal development. Furthermore, development nascent nephrons may contribute to expansion proximal part UCS. This study investigated distribution their interrelationship with UCS branches human embryogenesis. We obtained samples from 31 embryos Carnegie stages (CSs) 19 23 Kyoto Collection at Congenital Anomaly Research Center University in Japan. Serial histological sections metanephros were digitalized computationally reconstructed for morphological quantitative analyses. three-dimensional (3D) coordinates positions all branch points, end attachment points (APs), renal corpuscles (RCs) recorded related phase. Phases categorized phase 1 5 according analysis. branching continued until RCs first appeared (at CS19). End attached (EB-AP[+]) observed after CS19 fifth generation or higher embryonic period. range EB-AP(+) was broad, number increased stage, reaching 273.8 ± 104.2 CS23. connected exceeded not by 3D reconstructions revealed be distributed around branches, close surface metanephros. located away surface. APs remained near point, whereas connecting ducts that become tubules found elongate maturation RCs. Nascent RC phases 3-5 preferentially CS22 mean EB-AP(-) than 22 statistically significant eight ratio deviated pattern almost constant (29%). even total CS (9.2% CS21, 19.2% CS22, 45.4% CS23). Our data suggest following: further tip (i.e., splitting), but beneath AP (lateral branching) continues throughout stages. provides valuable can understanding interactions