5-350 Lecture Notes - Lecture 17: Neural Crest, Hypoplasia, Tricuspid Valve
Document Summary
Heart development: early heart development: cardiac crescent and heart tube. Only splanchnic mesoderm that migrates to the cardiac crescent become cardiogenic (committed to a cardiac fate) Cardiogenesis requires bmp-2 (which induces nkx2. 5 expr) and an unidentified factor tube. Cardiac crescent gives rise to 2 lineages: endocardial and myocardial cells. Two endocardial tubes form by vasculogenesis then fuse to form a single heart. Heart tube is composed of inner endocardium and outer myocardium with cardiac jelly in between, and is enclosed by pericardial cavity. A/p positional cues cause heart tube to segment into distinct regions. Heart tube folds right to left, and l/r asymmetry is induced by shh and nodal. Looping is regulated by ehand, which is downstream of nkx2. 5. Ventricular chamber growth follows looping, and is regulated by ehand in right ventricle and dhand in left ventricle; mef2c may be involved with both.