Department of Anatomy, University of Auckland, Private Bag, Auckland, New Zealand
The close anatomical and physiological relationship between the implanting blastocyst and the associated uterine epithelium was early indicated when Alden (1947) observed that lipid droplets became scarce or wanting in the apical regions of the maternal epithelial cells in the immediate neighbourhood of the rat blastocyst. However, neither Krehbiel (1937) nor Enders & Schlafke (1967) found significant changes in the uterine epithelial lipids, and Potts (1969) stated that at the time of implantation the lipid spread from the basal part of the cell to the supranuclear zone.
After biochemical analyses of whole uterine homogenates, Beall & Werthessen (1971) concluded that triglycerides, accumulated in the uterine tissues before implantation, were depleted from implantation sites by Day 7. Triglycerides are the principal components of neutral lipids, and these compounds vary in quantity and intracellular distribution within the rat uterine epithelium during