In vitro interactions of endometrial stromal and epithelial cells in Matrigel: reorganization of the extracellular matrix.

Fragments of human endometrial glands and dispersed endometrial stromal cells were cultured together in a thick layer of reconstituted basement membrane (Matrigel). Epithelial cells kept their glandular morphology whereas stromal cells grew into round clusters of mainly fusiform cells. Transmission electron micrographs showed collagen fibers between stromal cells as well as in surrounding extracellular matrix after 2.5 weeks. A well-defined basement membrane was found when epithelial and stromal cells were in close proximity to each other. Beneath the lamina densa there was a loose network of collagen fibers or a dense fibrillar network arranged parallel to the cell layers. Epithelial cells showed hemidesmosomes at their basal surface where they were close to stromal cells.