NCIt definition : An endometrial fibroblast that differentiates during pregnancy in response to the
implanting embryo by accumulating lipid and glycogen. It is polygonal, possesses a
large, vesicular nucleus and is believed to secrete placental prolactin. The decidual
cells form a tightly adherent, massive cellular matrix that first surrounds the implanting
embryo and later occupies most of the endometrium.;