Novel and efficient 3D microscopic analysis of isolated villous trees of human placentas

Abstract

The villous trees of human placentas delineate the fetomaternal border and are complex three-dimensional structures. Thus far, they are primarily analyzed from thin two-dimensional histological sections. Such sections cannot provide access to key aspects like branching nodes and branch order. As a consequence, histologic nomenclature of the villous tree does not include characterization of villous nodes. Using samples taken from 50 normal human placentas at birth, in the present study, we show that analysis procedures for the three-dimensional reconstruction of neuronal dendrite trees can also analyze villous trees of human placentas. We demonstrate how parameters of dendrite analysis can be adapted to the analysis of villous trees. Nodes and their branches (e.g., branching hierarchy, branching angles, diameters and lengths of branches) can be efficiently measured in whole-mount preparations of isolated villous trees using high-end light microscopy. Nodes are classified according to their distance from the terminal end of the villous trees. These novel data differ qualitatively from the data obtainable from histological sections and supplement such data. Since this novel method can be applied conveniently, an effective and technically feasible access to three-dimensional morphology of villous trees is opened.