[Verse 1] In the embryo's early days Paired aortic arches form in waves Left and right side by side they grow But only one is meant to show [Verse 2] Fourth arch on the left should stay While the right one fades away This normal pattern we must learn For when development takes a turn [Chorus] Left fourth persists, right regresses That's the normal way it processes But when right fourth takes control Conotruncal defects take their toll Aortic arch development Changes everything we've meant [Verse 3] Right aortic arch appears When the right fourth perseveres Left side fades instead of right Flipping what should be our sight [Verse 4] This anomaly we see Links to heart defects strongly Truncus arteriosus waits When development deviates [Chorus] Left fourth persists, right regresses That's the normal way it processes But when right fourth takes control Conotruncal defects take their toll Aortic arch development Changes everything we've meant [Bridge] Paired arches start the same But regression's not a game Fourth arch persistence decides the fate Will the heart develop straight [Chorus] Left fourth persists, right regresses That's the normal way it processes But when right fourth takes control Conotruncal defects take their toll Aortic arch development Changes everything we've meant [Outro] Remember this association clear Right arch and heart defects appear Embryology tells the tale When normal patterns start to fail
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