[Verse 1]
Day twenty marks the starting gun, a tube of flesh unfolds
Splanchnic mesoderm awakens, cardiac story told
Five chambers in a line they form, like beads upon a string
Sinus venosus catches blood, while truncus makes it sing
One vessel carries everything, no separation yet
A single pipe, a simple dream, before the complex net
[Chorus]
From tube to pump, the heart transforms
Week three to seven, life takes form
Neural crest cells migrate down
To split the single into two
D-loop bending, septa growing
Four chambers in their rightful place
The choreography of grace
[Verse 2]
Week four arrives with S-shaped curves, the tube begins to bend
Dextro-looping pulls it right, where ventricles transcend
Left and right find proper homes through this dramatic twist
One mistake in looping here, and normal pattern's missed
The bulbus cordis stretches out, future outflow tract
While primitive chambers rearrange, a cardiovascular pact
[Chorus]
From tube to pump, the heart transforms
Week three to seven, life takes form
Neural crest cells migrate down
To split the single into two
D-loop bending, septa growing
Four chambers in their rightful place
The choreography of grace
[Bridge]
Septum primum, septum secundum
Foramen ovale stays
Interventricular wall grows up
Muscular from below, membranous above
Meeting conotruncal division
Neural crest migration
Single truncus splits in two
Aorta, pulmonary, breakthrough
[Verse 3]
Weeks five through seven hold the key, conotruncal septation
Neural crest cells journey far from brain to destination
Without these wandering architects, the single vessel stays
Truncus arteriosus persists through all the baby's days
The spiral septum twists and turns, dividing what was one
Two great vessels emerge at last, the cardiac work is done
[Outro]
From single tube to four-chambered heart
Neural crest completes the art
When migration goes astray
Truncus arteriosus stays