Early Cardio Embryology Flashcards
A subset of what germ layer will be the precursor of most cells of the mature heart?
Precardiac mesoderm
What determines a precardiac cell’s fate?
Timing and entry point through the primitive streak, local proteins and transcription factors, environment (stress, hypoxia)
What layer provides precursors for portions of both myocardium and endocardium?
Lateral splanchnic mesoderm
What process consists of blood vessels arising from blood islands?
Vasculogenesis
What process consists of blood vessels sprouting from existing vessels?
Angiogenesis
What fuses to form the cardiogenic crescent? What happens at this crescent?
Primary heart fields fuse - this is where specific cells are segregated to their specific locations
What do cells of the first heart field form? What do they express?
Linear heart tube, left ventricle
Tbx5
What do cells of the second heart field (pharyngeal mesoderm) migrate to? What do they form? What do they express?
Migrate to cranial poles of heart tube
Outflow tracts, right ventricle, inflow tracts
Isll, Tbx1
What does third heart field give rise to? What do they express?
Horns of sinus venosus and periphery of inflow tract
Tbx18
After how many days does the heart tube begin to beat?
21-22 days
What does the truncus anteriosus segment of the primitive heart tube form?
Aortic and pulmonary trunks
What does the outlet segment of the primitive heart tube form?
Inlet and apical right ventricle; both outlets
What does the inlet segment of the primitive heart tube form?
Inlet and apical left ventricle
What does the atrium segment of the primitive heart tube form?
Atrial appendages
What does the sinus venosus segment of the primitive heart tube form?
Proximal SVC/IVC, smooth portion of right atrium
What types of genes are key in differentiation of multipotent precardiac cells? Name the specific gene in vertebrates.
Homeobox genes
Nkx2.5
What does Nkx2.5 activate?
Myocyte enhancement factors that control myocyte differentiations
Name the cranial to caudal ordering of precardiac cell migration through the primitive streak.
Those migrating first form outflow tracts, then RV, LV, primitive atrium, sinus venosus
What types of proteins inhibit heart formation?
WNT
What type of looping does the linear heart tube undergo in vertebrates?
Rightward (D-looping)
What type of bHLH transcription factors are primarily expressed by right ventricular segments?
HAND 2
What type of bHLH transcription factor is primarily expressed by left ventricular segments?
HAND1
Deletion of what gene results in right ventricular hypoplasia?
HAND2
Describe the direction in which the cephalic portion of the linear heart tube bends.
Ventrally, caudally, to the right
Describe the direction in which the atrial/caudal portion bends.
Dorso-cranially and to the left
What convergence results due to looping?
Convergence of inflow (venous) and outflow (Arterial) ends
