Morphogenesis and postulated functions of decidual cells.

Decidual cells are a morphologically distinct cell population arising in the endometrium during pregnancy. Decidualisation can also be elicited by artificial stimuli in suitably hormone primed animals. A variety of histophysiological reactions accompany decidualisation and culminate in the differentiation of endometrial stromal cells to decidual ones. Typical ultrastructural features characterise antimesometrial and mesometrial decidual cells. The functional role of these cells is consistent with their structural complexities and definite life span. The metrial gland forms a separate class of cells associated with decidualisation. Recent observations on the origin of both decidual and metrial gland cells from the bone marrow suggest an immunological role.