Human endometrial cells grown on an extracellular matrix form simple columnar epithelia and glands

Normal human endometrial cells were grown on an extracellular matrix containing type IV collagen, laminin, heparan sulfate proteoglycan, and entactin (Matrigel). On the extracellular matrix, dispersed endometrial cells remained rounded, and aggregated to form mounds of cells, which continued to grow in this arrangement. At 10 d, light microscopy demonstrated that these mounds were comprised of an eosinophilic substance, containing individual fusiform stromal cells. About 50% of the mounds were covered with a single layer of polarized cuboidal to columnar cells with basal nuclei, whereas 60% contained columnar cells forming glandular structures with open lumina. These polarized cuboidal and columnar cells were epithelial, based on their positive staining for cytokeratins and the possession of microvilli, tonofilaments, abundant glycogen, ribosomes, and primitive junctional complexes. Kreyberg's stain showed the presence of mucin within the lumina of the glands, indicating that they were functional. Thus, human endometrial cells grown on an extracellular matrix form a simple cuboidal to columnar epithelium, a stromal component, and glandular structures, thereby mimicking the in vivo morphology of the endometrium.