Decidual Cell

**Semantic type:** Cell

**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.