[Verse 1]
Day twenty comes and life begins to beat
A single tube of heart so incomplete
Five chambers lined up straight in a row
Sinus to truncus, watch the blood flow
Splanchnic mesoderm forms the primitive start
One pipe, one vessel, a simple heart
[Chorus]
From tube to pump in seven weeks' time
D-loop and septate, everything's aligned
Neural crest cells migrate down below
Split the truncus, make two vessels grow
Aorta, pulmonary, side by side
Normal development, our perfect guide
[Verse 2]
Week four arrives, the bending starts
S-shaped looping moves the parts
Dextro-looping to the right
Ventricles finding position just right
If this goes wrong, the heart's misplaced
But normal looping keeps it all in space
[Chorus]
From tube to pump in seven weeks' time
D-loop and septate, everything's aligned
Neural crest cells migrate down below
Split the truncus, make two vessels grow
Aorta, pulmonary, side by side
Normal development, our perfect guide
[Verse 3]
Weeks four through seven, the walls appear
Septa divide what once was clear
Interatrial splits the common space
Foramen ovale keeps the fetal pace
Interventricular grows from the floor
Muscular first, then membranous more
[Bridge]
Conotruncal septation is the key
Neural crest cells set the vessels free
From brain and spine they travel far
To split the trunk where two tubes are
Without these cells, truncus remains
One vessel where there should be twains
[Chorus]
From tube to pump in seven weeks' time
D-loop and septate, everything's aligned
Neural crest cells migrate down below
Split the truncus, make two vessels grow
Aorta, pulmonary, side by side
Normal development, our perfect guide
[Outro]
When septation fails, truncus stays whole
One vessel playing both vessels' role
But when it works, the heart's complete
Four chambers strong with perfect beat