Article

Cell and Tissue Research

, Volume 177, Issue 1, pp 105-121

First online:

The villous stroma of the human placenta

I. The ultrastructure of fixed connective tissue cells
  • P. KaufmannAffiliated withAnatomisches Institut der Universität Hamburg and Universitäts-Frauenklinik Hamburg
  • , J. StarkAffiliated withAnatomisches Institut der Universität Hamburg and Universitäts-Frauenklinik Hamburg
  • , H. E. StegnerAffiliated withAnatomisches Institut der Universität Hamburg and Universitäts-Frauenklinik Hamburg

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Summary

In human placental villi the connective tissue is constructed by mesenchymal cells, small and large reticulum cells and fibroblasts. During early pregnancy mesenchymal cells dominate; starting with the third month of gestation the reticulum cells are in the majority within the terminal villi, the fibroblasts within the stem villi. Ultrastructurally intermediary types of cells can be differentiated. Together with reticular and collagenous fibres the reticulum cells form the basic architecture of the villous stroma during the first 2/3 of gestation: the “reticular type of stroma”. This consists of a network of cells and fibres with fetal vessels fitted in between. The remaining interspaces form a fluid system of compartments in which Hofbauer cells are suspended. They are called stromal channels. During the last trimester these channels and the Hofbauer cells as well are progressively replaced either by voluminous masses of fibres (“fibrous type of stroma”, mainly in the stem villi) or by sinusoidal enlargements of fetal capillaries (“sinusoidal type of stroma”, mainly in the terminal villi).

Key words

Human placenta Villous stroma Fixed stromal cells Ultrastructure