The human placenta is a meticulously structured organ, whose functional effectiveness is contingent on the spatial and microanatomical arrangement of the chorionic villi's tree-like network. Recent advancements in three-dimensional (3D) imaging techniques have enabled in-depth examination of the hierarchical structure, vascularization, and branching patterns of these villi. This progression has facilitated the correlation of structural characteristics with the functionality of utero-fetal exchange. The purpose of this scoping review is to systematically map and synthesize the existing literature on the 3D architecture and branching patterns of chorionic villi in the normal human placenta. A comprehensive investigation was carried out using PubMed and Scopus databases, yielding 11 and 295 articles, respectively, from which 40 were deemed pertinent for this study. The available evidence indicate that the villous tree in a normal human placenta presents a highly structured hierarchy, established early in gestation. The terminal villi possess intricate capillary networks characterized by loops, anastomoses, and fixed angles of branching, all of which minimize diffusion distances and enhance blood flow. The close spatial proximity of vessels, stroma, and syncytiotrophoblast not only provides mechanical stability but also facilitates effective gas and nutrient exchange. The 3D configuration of placental villi forms a functionally optimized, hierarchical system that meets the hemodynamic and metabolic requirements of pregnancy. The deployment of advanced imaging and morphometric techniques has transitioned placental research from solely anatomical description to more mechanistic and predictive frames.
Sinou et al. (Tue,) studied this question.