1.3primitivecardiovascularsystem1Hearttubes:two tubes -→ one tube-→primitiveheartArteries:Veins:3AntCommon.cardinalveincardinal veindorsoltnterlertioryvilluDorsalaortaAorticarchesanlerior.cordinaldorsal(ll and i)nectingstallonoPost.cardinal veinheartIntChorioniccarotidtubeumbilicovillusarteryHeartAorticsacVitellineveinvhellinveinsarleriesChoriorUmbilical veinVitellineyolksnandarteryartery
1.3 primitive cardiovascular system: ① Heart tubes: two tubes → one tube →primitive heart ② Arteries: ③ Veins:
1.3primitivecardiovascularsystem:Hearttubes:12dorsalA-→1 dorsalaorta withmany branches:Arteries:few pairs of vitelline A1pairofumbilicalA6 pairs of aorticarchesVeins:AntCommoncardinalveincardinal veindorsol inerseamsntal artarietertioryvillusDorsalaortaAortic archesanterior cordinaldersalconnecting(lland il)veinoortotitallPost.cardinal veinheonInt.ChorioniccarotidtubesumbiicovillusarteryHeartAorticsacVitellinevaelinevein-viinsnorionUmbilical veirVitellineollaandarteryartery
1.3 primitive cardiovascular system: ① Heart tubes: ② Arteries: ③ Veins: 2 dorsal A →1 dorsal aorta with many branches: few pairs of vitelline A 1 pair of umbilical A 6 pairs of aortic arches
1.3primitive cardiovascular system:Heart tubes:1Arteries:21 pair of anterior cardinal veinCommoncardinalvein1 pair of posterior cardinal vein3Veins:1 pair of vitelline vein1 pair of umbilical veinAnt.Commoncardinalveincardinal veindorsal inmersegmental artariestertoryvilluDorsalaortaAorticarchesinterior.cordinaldersalconnecting(lland Il)veinsstallPost.cardinal veinheorIntChorioniccarotidtubeumbilcovillusarteryarterseHeartAorticsac-Vitellinevein-vellnilicolveinstarehorionUmbilicalveinVitellineyolksoeandarteryartery
1.3 primitive cardiovascular system: ① Heart tubes: ② Arteries: ③ Veins: 1 pair of anterior cardinal vein 1 pair of posterior cardinal vein 1 pair of vitelline vein 1 pair of umbilical vein Common cardinal vein
1.3primitivecardiovascularsystem3 separate circulations→vitelline,chorionic,andintraembryoniccirculation.弓动脉Aortic arches天静脉窦Sinus venosus动脉囊前、总和恋n后主静脉HeartAnterior,posteriorand_commoncardinal vein背节间动脉rsegmentalDorsal in卵黄囊arteryYolk sac背主动脉Dorsal aorta卵黄动脉Vitelline artery左脐动脉脐静脉（右侧未显示）Umbilical veinLeft umbilical artery(Therightonenotshown)脐带Umbilical cord
1.3 primitive cardiovascular system 3 separate circulations → vitelline, chorionic, and intraembryonic circulation
2. Outer form of the heart2.1 Development of PrimitiveHeart Tube2.2 Formation of Heart LoopTruncusarteriosBulbuscordisVentricleAtriumSinus venosusntricleAtriumSinusuVentricle
2.1 Development of Primitive Heart Tube 2.2 Formation of Heart Loop 2. Outer form of the heart