1. 1 Historical Aspects and Terminology Granulated metrial gland (GMG) cells are readily identified by their cytoplasmic granules and were observed a number of years before the term "metrial gland" was introduced. A series of papers by Duval in 1891 provided a comprehensive description and a critical review of earlier studies of the placenta of rodents, but it was not until 1902 that the first convincing illustrations of GMG cells appeared in the literature (Jenkinson 1902). Jenkinson described "maternal glycogen cells" in the pregnant mouse uterus and noted that they contained cytoplasmic...