2)头褶:心管→围心腔背侧 口咽膜尾侧 A Connecting Cardiogen Neural plate stalk Allantois Al Prochordal Notochord Amniotic Cloacal membrane cavI AT B1 Hindgut Heart tube pericardial Buccopharyngeal Dorsal B1 membrane cavity mesocardium Pericardial Cloacal membrane HOME2) 头褶：心管→ 围心腔背侧 ↘ 口咽膜尾侧