The chorion functions to separate the amnion from the maternal decidua and uterus. Thus the placenta develops from the chorion frondosum and the decidua basalis. The underlying chorion is fused to the decidua at the maternal-fetal interface. During pregnancy it is also produced by the placenta, chorion, and decidua. Further, the decidua has to allow a very controlled invasion of the trophoblast. Endometrium on the opposite side to the decidua basalis is the decidua parietalis. The decidua is shed with the placenta during birth. In females, it is present in the ovaries, oviducts myometrium, decidua, and placenta. The compacta and spongiosa layers are still observable beneath the decidua in pregnancy. The decidua becomes part of the placenta; it provides support and protection for the gestation. These models display abnormally low amounts of cells or necrosis of decidua. CCL8 is also involved in attracting macrophages to the decidua in labor. Capparis decidua (kair) and Calotropis gigantea (aak pkant) were also used. After implantation the decidua remains, at least through the first trimester. "decidua", which was applied by C.D. Beadle in 1914 upon noticing the deciduous leaves.