BIOL 3010 Lecture Notes - Autocrine Signalling, Fibrillin, Interatrial Septum
29 Jan 2013
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Cardiac crescent / heart tube splanchnic mesoderm (anterior, ventral lateral plate) diff. into: Cardiac induction (muscle) myocardial precursors acquire cardiac fate in cardiac crescent (examined by watching for heartbeat in cell culture, nkx2. 5) fate acquired at cardiac crescent: Inductive bmp-2 signal from anterior endoderm (lateral anterior endoderm can induce cardiogenesis in grafted posterior mesoderm) However, bmp-2 can only induce heart formation in anterior regions must be a second signal that is expressed anteriorly. Nkx 2. 5 not essential, but earliest marker of cardiac fate. Heart looping coverts the a-p axis into l-r asymm. heart folds leftward (dextrocardia rightward fold) L/r patterning: shh and nodal expression patterns defects in either cause situs inversus, randomization nodal expressed on left normally. **looping is important for aligning chambers with vasculature** ehand tf expressed in left ventricle only thought to cause looping by promoting asymmetric proliferation of cardiac myocytes. Nkx 2. 5 activates ehand txn dhand expressed in rv; also promotes asymmetric growth.
