Decidualization of the endometrium, mainly induced by progesterone, is a process of endometrial remodelling where the endometrial stromal cells differentiate into secretory decidual cells in preparation for pregnancy. Decidualized endometrial stromal cells are characterized by release of prolactin （PRL）, RI-like growth factor binding protein-1 （IGFBP-1）, tissue factor （TF）, plasminogen activator inhibitor-1 （PAI-1）, and expression of basal lamina components such as laminin, collagen IV, and fibronectin. Immortalised Human Endometrial Stromal Cells （HESC） are unique in that 1） they display normal karyotype and 2） they respond to hormone stimulation and retain the morphological pattern and biochemical endpoints of decidualization after treatment of oestradiol and medroxyprogesterone, making this cell line a valuable tool in endometrium homeostasis and female reproductive studies.
