Germ

**Embry** is a multicellular embryonic organism formed from a fertilized egg and developing in the mother’s body or under artificial conditions. The development of the embryo leads to the formation of easily distinguishable (blastocyst) or indistinguishable cells. Due to the differentiation of various specialized cells of blastomeres, cells of all germinal membranes (allantois, amnion) and three germ layers are formed - outer (ectoderm), middle (endoderm) and inner (mesoderm). In the embryos of invertebrate animals, trophoblast, gastrula and then blastulogenesis are first formed. During the zygote cleavage, cells involved in the formation of the blastomere