Granulated metrial gland cells in the uterine wall and placenta of the pregnant woodmouse, Apodemus sylvaticus.

The differentiation of the decidua and the fetal placenta in the woodmouse, Apodemus sylvaticus, was studied with particular attention to the differentiation and migration of granulated metrial gland cells. Numerous granulated metrial gland cells, characterised by their glycoprotein-containing cytoplasmic granules, were found to differentiate in the decidua basalis and metrial gland of the uterine wall during the first half of pregnancy. Many granulated metrial gland cells appeared to pass into the lumina of blood vessels in the uterine wall and reach the maternal blood spaces of the fetal placenta. In the labyrinthine placenta some granulated metrial gland cells were found associated with degenerate cytotrophoblast lining the maternal blood spaces. This finding supports previous studies of the mouse, Mus musculus, suggesting that the labyrinthine placenta is an important site for the function of the bone marrow-derived granulated metrial gland cell.