2. 2C = diploid DNA content 2C most cells skeletal muscle syncytiotrophoblast mitosis 2C cell fusion mitosis 2C endomitosis 4C cardiomyocytes hepatocytes megakaryocytes endoreduplication 4C no karyokinesis or cytokinesis 8C trophoblast giant cells endoreduplication

3. multi-layered chorion 2 layers of syncytiotrophoblast sinusoidal trophoblast giant cells The Labyrinth mural trophectoderm “primary” parietal trophoblast giant cells “secondary” parietal trophoblast giant cells canal trophoblast giant cells spiral artery- associated trophoblast giant cells glycogen trophoblast cells ectoplacental cone/ spongiotrophoblast cells trophoblast stem cells polar trophectoderm inner cell mass mural trophectoderm The Junctional Zone Gcm1 Hand1 Igf2 Mash2 Cdx2, Err2