The cytoskeleton of uterine epithelial cells: a new player in uterine receptivity and the plasma membrane transformation.

During early pregnancy and the period of blastocyst attachment, the plasma membrane of uterine epithelial cells, which is the first site of contact between maternal and fetal cells, undergoes a remarkable change in configuration, with morphological and biochemical alterations occurring apically and basolaterally. These alterations are collectively referred to as 'the plasma membrane transformation' of early pregnancy. It would be remarkable if this transformation did not also involve alterations in cytoskeletal elements and, in particular, the membrane-associated cytoskeleton. This review therefore, after an overview of the morphological and molecular aspects of the membrane transformation as background, proceeds to examine what is known about the cytoskeleton of uterine epithelial cells. Cytoskeletal elements particularly associated with the plasma membrane are then examined and some new approaches to understanding membrane-skeletal dynamics, including detergent-permeabilization techniques for transmission and high-resolution scanning electron microscopy of uterine epithelial cells, are reported, together with recent work on these structures. The review concludes with an examination of how membrane-skeletal elements could contribute to the membrane transformation.