An organism between the time of conception and hatching or birth. In mammalian development, the period of the embryo comprises the span from the first cell divisions until the organism begins to take the form of the adult, when it is referred to as a fetus (at about 7 weeks post-conception). Mammalian embryos are all but indistinguishable from each other with the naked eye (see figure below).
A. Cat, B. Cow, C. Horse, D. Human. Each embryo at the stage when limb buds have formed.
Epithelium,See Adhesion molecules, Anlage, Antenatal, Behavioral embryology, Blastula, Dorsal plate in limb bud, Ectoderm, Embryogenesis, Entoderm (or endoderm), Fetus, Hypomorphic nervous system, Infancy/infant, Invagination, Limb bud, Mesenchyme, Mesoderm, Morula, Motility, Newborn, Toddlers, Ventral plate in limb bud