title: Electron microscopic observations on the yolk sac of the spiny dogfish, Squalus acanthias.
mesh_terms: D000818:Animals; D005321:Extraembryonic Membranes / Q000166:cytology* / Q000502:physiology; D005260:Female; D006056:Golgi Apparatus; D008854:Microscopy, Electron; D011247:Pregnancy; D011270:Pregnancy, Animal; D012754:Sharks