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- 2. Objectives Formation of the trilaminar embryo Origin of cardiogenic cells Formation of bilateral heart fields Formation of the heart tube Folding of the heart tube Looping of the heart tube Cardiac developmental abnormalities
- 3. Day 0 : Fertilisation forming zygote initiating embryogenesis 2 cell stage; 4 cell stage; morula Week 1 : implantation ( as a blastocyst) Week 2 : bilaminar stage (epiblast,hypoblast) Week 3 : gastrulation ;primitive streak,notochord and neural plate begin to form Week 4: heart begins to form
- 4. Cardiovascular system – develops from mesoderm Specifically, splanchnic lateral plate mesoderm
- 5. The cardiogenic field is established in the mesoderm just after gastrulation (~18-19 days) and develops into a fully functional, multi-chambered heart by the 8th week angiogenic cell clusters (angioblasts/hemangioblasts) (right dorsal aorta) (right endocardial tube) blood islands (developing blood vessels) cardiogenic field pericardial cavity Langman’s fig 12-1
- 6. Cardiogenic area- cranial end between septum transversum and prochordal plate
- 7. • Intraembryonic coelom – pericardial cavity • Splanchnopleuric mesoderm underneath pericardial cavity – Primitive heart tube
- 9. • Heart tube – endocardium of heart • Splanchnic mesoderm – myocardium and Epicardium
- 10. After folding
- 11. Cardiogenic cords get canalized to form two endothelial heart tubes
- 12. PARTS OF THE HEART TUBE
- 13. Arterial end: • Truncus Arteriosus – continuous with aortic sac having right and left horns • Each horn – first pharyngeal arch artery arises, - Continuous with respective dorsal aorta
- 14. Venous end: Sinus venosus Receives three primitive veins: • Vitelline vein – yolk sac • Umbilical vein – placenta • Common cardinal vein – body wall
- 15. EMBRYONIC DILATATION ADULT DERIVATIVES Truncus arteriosus Ascending Aorta and Pulmonary trunk. Bulbus cordis. . Smooth part of Right Smooth part of Left ventricle(aortic vestibule) Primitive ventricle Trabeculated part of Right ventricle.and Trabeculated part of Left ventricle Primitive Atrium Trabeculated part of Right atrium Left Trabeculated part of atrium Sinus venosus Smooth part of Right atrium(sinus venarum) coronary sinus oblique vein of the Left atrium FATE OF VARIOUS DILATATIONS OF HEART TUBE
- 16. • Heart tube lies in the floor of pericardial cavity After head fold, undergoes 180 rotation, heart tube lie on the roof of pericardial cavity Moore & Persaud fig 13-9 Positioning of Heart tube in relation to pericardial cavity
- 17. Formation of Cardiac wall • Endocardium– endothelial heart tube • Myocardium- myoepicardial mantle • Epicardium- myoepicardial mantle
- 18. External adult form of heart Cardiac loop Dorsal mesocardium
- 24. DEXTRO CARDIA • All the chambers of the heart and associated blood vessels are reversed as a mirror image • Heart tube bends to left • Associated with situs inversus Clinical correlation
- 25. ECTOPIA CORDIS • rare condition in which is Heart is exposed on the surface of the Thorax. • Due to nonunion of two pieces of developing sternum.
- 26. Single lumen primitive heart tube is partitioned into Four chambers by the formation of four septa: 1.Atrioventricular septum. 2. Interatrial septum. 3. Interventricular septum. 4. Aorticopulmonary septum Development of various chambers of Heart
- 27. Formation of Atrio-ventricular septum • AV septum divides the AV canal into right and left AV canal • Two thickenings appear – one on dorsal and one on ventral wall – endocardial cushions or AV cushions