EMB development of the heart

what are cardiac progenitor cells

cells originated from intraembryonic splanchic mesoderm at the cranial third end of the primitive streak, they migrate cranial laterally due to signals from endoderm, ectoderm and midline mesoderm, forming the primary heart field (=cardiac crescent) cranial to the neural folds

what effect does the retoinic acid gradient have

the most posterial cells develop an atrial identity while the anterior cells develop a ventrical identity

name the two other sources of cardiac progenitor cells

1. secondary heart field (develops right ventricle and outflow tract)

2. proepicardium (develops the epicardium (outer heart layer), interstitial connective tissue and coronary vasculature)

what develops from the cardiac crescent/primary heart field

left ventricle and atria

how is the primitive heart tube formed

by lateral folding of the endocardial tubes (they come together) and fuse in the midline of the embryo. its then extended with cells from the secondary heart tube (the cranial part becomes atrial and the caudal part ventrical)

how is the furture thorax formed

by cranial folding of the endocardial tubes

name the layers of the heart tube

1. endocardium (inner lining)

2. myocardium (muscle cells)

3. Jelly coat (ECM between endo and myocardium)

4. epicardium (protective outer layer of proepicardium = splanchic mesoderm), later forms coronary vasculature

the primitive heart tube has 1 lumen which develops into 4 chambers, name these chambers

1. sinus venosus (at inflow end)

2. primitive atrium

3. primitive ventricle

4. bulbus cordis

what structures does the sinus venosus become part of

the sinus vinosus consist of the left and right sinus horns, which become part of the RA and superior vena cava

what loops do the 4 chambers make

• Bulbus cordis → caudal, right → forms part of right ventricle, conus cordis and truncus arteriosus

• Primitive ventricle → left → forms left ventricle        

• Primitive atrium→ cranial, dorsal → forms left and right atria   

• Sinus venosus → inflow region → forms right atrium + SVC

• Outflow tract lies between atria

what are the 2 subdivisions of the bulbus cords

1. the conus cordis

2. the truncus arteriosus (will split into ascending aorta and pulmonary trunk)

division of outflow tract:

conotrucnal ridges form in conus arteriosus & truncus arteriosus, which fuse into the conotruncal septum:

which spirals to align the right ventricle with the pulmonary artery and align th eleft ventricle with the aorta

why is division of outflow tract important

bc it ensures seperation of systemic and pulmonary circulations

Key Embryological Structures and Their Adult Derivatives

• Primary heart field          

• Secondary heart field

• proepicardium

• bolbus cordis

• primitive ventricle

• primitive atrium

• sinus venosus

• truncus arteriosus

• primary heart field → LV and atria

• secondary heart field → RV, outflow tract

• proepicardium → epicardium & coronary vessels

• bulbus cordis → RV

• primitive ventricle → LV

• primitive atrium → LF & R atria

• sinus venosus → RA & SVC

• truncus arteriosus → ascending aorta and pulmonary trunk

what are the 2 layers of the epicardium

1. inner epicardiium

2. visceral pericardium

how are the ventricles partially seperated

by formation of the interventricular septum

how do the 2 ventricles communicate

through the interventricular foramen

how does the dividion of the outflow tract start

by conotruncal swelling or bc ridges form in the conus arteriosus and truncus arteriosus which fuse to form the conotruncal septum

how is division of outflow tract complete

when the interventricular septum fuses with the conotruncal setum and atrioventricular septum