title: The extra-embryonic coelom on ultrasonography.
mesh_terms: D000328:Adult; D004622:Embryo, Mammalian / Q000502:physiology*; D005314:Embryonic and Fetal Development; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D014463:Ultrasonography