Septum formation in AV Canals outflow tract (1).pptx

Embryology presentation.

1. Septum Formation in AV Canals and Outflow Tract

2. Describe the septum formation in outflow tract and AV canals of primitive heart. Relate the outflow tract defects with their normal developmental process. Topics

3. Septum Formation between the 27 th and 37 th days

4. Two actively growing masses of tissue that approach each other until they fuse Dividing the lumen into two separate canals Depends on synthesis and deposition of extracellular matrices and cell migration and proliferation Endocardial cushions

5. Develop in the atrioventricular and conotruncal regions Atrial septa Ventricular septa (membranous portion) Atrioventricular canals Atrioventricular valves Aortic and pulmonary channels

6. Neural crest cells Migrating from the cranial neural folds to the outflow tract region Conotruncal cushions

7. Septum Formation in the Atrioventricular Canal

8. Bulboventricular flange

9. Atrioventricular Valves

10. Regulation of epithelial to mesenchymal transformation

11. After the atrioventricular endocardial cushions fuse Atrioventricular orifice is surrounded by local proliferations of mesenchymal tissue derived from the endocardial cushions

12. When the bloodstream hollows out and thins tissue on the ventricular surface of these proliferations Mesenchymal tissue becomes fibrous and forms the atrioventricular valves , which remain attached to the ventricular wall by muscular cords

13. Muscular tissue in the cords degenerates and is replaced by dense connective tissue The valves then consist of connective tissue covered by endocardium They are connected to thick muscular trabeculae in the wall of the ventricle, the papillary muscles , by means of chordae tendineae

14. Septum Formation in the Truncus Arteriosus and Conus Cordis

15. When partitioning of the TA is completed, the semilunar valves begin to develop From three swellings of subendocardial tissue around the orifices of the aorta and pulmonary trunk Cardiac precursor neural crest cells also contribute

16. These swellings are hollowed out and reshaped to form three thin-walled cusps

17. Developmental Anomalies

18. Involves obliteration of the right atrioventricular orifice Characterized by the absence or fusion of the tricuspid valves Tricuspid atresia

19. Tricuspid valve is displaced toward the apex of the right ventricle There is an expanded right atrium and a small right ventricle The valve leaflets are abnormally positioned, and the anterior one is usually enlarged Ebstein anomaly

20. Occurs when the semilunar valves are fused for a variable distance The incidence of the abnormality is 3 to 4/10,000 births In the case of a valvular stenosis of the pulmonary artery, the trunk of the pulmonary artery is narrow or even atretic Valvular stenosis of the pulmonary artery

21. Fusion of the thickened valves may be so complete that only a pinhole opening remains The size of the aorta itself is usually normal Aortic valvular stenosis

22. When fusion of the semilunar aortic valves is complete The aorta, left ventricle, and left atrium are markedly underdeveloped The abnormality is usually accompanied by an open ductus arteriosus , which delivers blood into the aorta Aortic valvular atresia

23. Tetralogy of Fallot

24. Transposition of the great vessels

25. DiGeorge Sequence

26. Thankyou