The nature of the earliest spontaneous activity of the chick embryo.
D000818:Animals; D002642:Chick Embryo / Q000033:anatomy & histology* / Q000502:physiology*; D005321:Extraembryonic Membranes; D008648:Mesoderm / Q000637:transplantation*; D009132:Muscles / Q000502:physiology*; D013116:Spinal Cord / Q000637:transplantation*