Cardiac Septation UNSW Embryology Heart - day 40 (ventral view)

primordial right atrium primordial left atrium primordial left ventricle primordial right ventricle fused endocardial cushions sinus venosus opening Heart - day 40 (ventral view) Dorsal and ventral endocardial cushions fuse, generating left and right channels

primordial right atrium primordial left atrium primordial left ventricle primordial right ventricle fused endocardial cushions sinus venosus opening Heart - day 40 (ventral view) Dorsal and ventral endocardial cushions fuse, generating left and right channels

Septum primum - myocardium differentiated from splanchnic mesenchyme near the venous pole septum primum

Septum primum grows downward towards fused endocardial cushions

septum primum foramen primum Septum primum growth Septum primum growth generates foramen primum

septum primum foramen primum Septum primum growth Septum primum growth generates foramen primum

septum primum foramen primum Septum primum growth Septum primum - myocardium differentiated from splanchnic mesenchyme near the venous pole

septum primum foramen primum Septum primum growth

Septum primum perforation begins to degenerate to form opening Septum primum perforation begins to degenerate to form opening

Ventricular septum growth

sinus venosus valve pulmonary veins opening ventricular septum Septum primum perforates and the ventricular septum begins growth Septum primum perforates and the ventricular septum begins growth

sinus venosus valve pulmonary veins opening ventricular septum Septum primum now perforates and the ventricular septum begins growth Septum primum now perforates and the ventricular septum begins growth

Ventricular septum growth ventricular Septum Ventricular septum growth Early studies thought that the ventricular septum formed from coalescence of trabeculae of the primordial ventricle Ventricular septum growth Early studies thought that the ventricular septum formed from coalescence of trabeculae of the primordial ventricle

Ventricular septum growth ventricular Septum Ventricular septum growth Early studies thought that the ventricular septum formed from coalescence of trabeculae of the primordial ventricle Ventricular septum growth Early studies thought that the ventricular septum formed from coalescence of trabeculae of the primordial ventricle

ventricular septum

Ventricular septum Ventricular septum growth Later studies show the muscular septum arises from fusion of the external R and L ventricular walls with ventricular growth Ventricular septum growth Later studies show the muscular septum arises from fusion of the external R and L ventricular walls with ventricular growth

Ventricular septum Ventricular septum growth Later studies show the muscular septum arises from fusion of the external R and L ventricular walls with ventricular growth Ventricular septum growth Later studies show the muscular septum arises from fusion of the external R and L ventricular walls with ventricular growth

Septum secundum growth

Ventricular trabeculation

Septum secundum growth septum secundum foramen secundum foramen ovale

Septum Secundum forms as a superior interarterial fold septum secundum

Septum Secundum forms as a superior interarterial fold septum secundum

Septum Secundum Septum secundum also from the original cardiogenic fields left sided mesenchyme

Septum Secundum Septum secundum also from the original cardiogenic fields left sided mesenchyme

Ventricular Trabeculation…something about this process

trabeculae