Proliferative versus hypertrophic growth in tissue subcompartments of human placental villi during gestation.

A cross-sectional sample of human placentae was collected at 12-41 wk, and growth mechanisms within villous subcompartments (trophoblast epithelium, stroma and fetal capillary endothelium) were assessed using state-of-the-art design-based stereological methods. Physical disectors (adjacent pairs of sections) were used to count nuclei in syncytiotrophoblast and in cells of the cytotrophoblast, stroma and endothelium. The volumes of trophoblast and stroma and the surface areas and lengths of capillaries were employed to assess the overall growth of each compartment.

Placental morphogenesis and the star volumes of villous trees and intervillous pores.

In 27 human placentae collected at 13-39 weeks, the growth and morphogenesis of villi and of the maternal intervillous space were assessed using a design-based stereological approach for estimating star volume. The purpose was to quantify changes occurring during these processes and to derive parameters pertinent to physiological performance (notably transport capability and haemodynamics). Placentae were sampled by cutting paraffin sections at random locations and orientations.