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extraembryonic cells that, although derived from the zygote, are not part of the embryo proper and contribute to the fetal membranes (for example, amnion).
Synonym(s): primary mesoderm
Etymology: L, extra, outside; Gk, en + bryein, to grow, mesos, middle, derma, skin
any mesoderm in the uterus that is not involved with the embryo itself. Included are mesoderms in the amnion, chorion, yolk sac, and connecting stalk.
Mesoderm lying outside the embryo proper and involved in the formation of amnion, chorion, yolk sac, and body stalk.
See also: mesoderm
the middle of the three primary germ layers of the embryo, lying between the ectoderm and entoderm; from it are derived the connective tissue, bone, cartilage, muscle, blood and blood vessels, lymphatics, lymphoid organs, notochord, pleura, pericardium, peritoneum, kidneys and gonads.
located outside the developing embryo and forming its accessory organs.
adjacent to the mid line beneath the epiblast of the embryo which develop into somites.
the outer layer of the developing mesoderm.
the inner layer of the developing mesoderm.