(一)原始咽的演变 ρ鳃器官ε鳃弓、鳃沟、鳃膜、咽囊 Cranial neuropore 1 st and 2 Otic placode Pharyngeal pharyngeal Pharyngeal clefts Pericardia arches arches bulge Cut edge Lens of amnion placode Limb Heart bud Vitelline duct bulge Umbilical Connecting cord Pericardial stalk-oy swelling A Caudal B neuropore(一)原始咽的演变 • 鳃器官：鳃弓、鳃沟、鳃膜、咽囊