Early Cardio Embryology

Question 1

A subset of what germ layer will be the precursor of most cells of the mature heart?

Answer 1

Precardiac mesoderm

Question 2

What determines a precardiac cell’s fate?

Answer 2

Timing and entry point through the primitive streak, local proteins and transcription factors, environment (stress, hypoxia)

Question 3

What layer provides precursors for portions of both myocardium and endocardium?

Answer 3

Lateral splanchnic mesoderm

Question 4

What process consists of blood vessels arising from blood islands?

Answer 4

Vasculogenesis

Question 5

What process consists of blood vessels sprouting from existing vessels?

Answer 5

Angiogenesis

Question 6

What fuses to form the cardiogenic crescent? What happens at this crescent?

Answer 6

Primary heart fields fuse - this is where specific cells are segregated to their specific locations

Question 7

What do cells of the first heart field form? What do they express?

Answer 7

Linear heart tube, left ventricle

Tbx5

Question 8

What do cells of the second heart field (pharyngeal mesoderm) migrate to? What do they form? What do they express?

Answer 8

Migrate to cranial poles of heart tube

Outflow tracts, right ventricle, inflow tracts

Isll, Tbx1

Question 9

What does third heart field give rise to? What do they express?

Answer 9

Horns of sinus venosus and periphery of inflow tract

Tbx18

Question 10

After how many days does the heart tube begin to beat?

Answer 10

21-22 days

Question 11

What does the truncus anteriosus segment of the primitive heart tube form?

Answer 11

Aortic and pulmonary trunks

Question 12

What does the outlet segment of the primitive heart tube form?

Answer 12

Inlet and apical right ventricle; both outlets

Question 13

What does the inlet segment of the primitive heart tube form?

Answer 13

Inlet and apical left ventricle

Question 14

What does the atrium segment of the primitive heart tube form?

Answer 14

Atrial appendages

Question 15

What does the sinus venosus segment of the primitive heart tube form?

Answer 15

Proximal SVC/IVC, smooth portion of right atrium

Question 16

What types of genes are key in differentiation of multipotent precardiac cells? Name the specific gene in vertebrates.

Answer 16

Homeobox genes

Nkx2.5

Question 17

What does Nkx2.5 activate?

Answer 17

Myocyte enhancement factors that control myocyte differentiations

Question 18

Name the cranial to caudal ordering of precardiac cell migration through the primitive streak.

Answer 18

Those migrating first form outflow tracts, then RV, LV, primitive atrium, sinus venosus

Question 19

What types of proteins inhibit heart formation?

Answer 19

WNT

Question 20

What type of looping does the linear heart tube undergo in vertebrates?

Answer 20

Rightward (D-looping)

Question 21

What type of bHLH transcription factors are primarily expressed by right ventricular segments?

Answer 21

HAND 2

Question 22

What type of bHLH transcription factor is primarily expressed by left ventricular segments?

Answer 22

HAND1

Question 23

Deletion of what gene results in right ventricular hypoplasia?

Answer 23

HAND2

Question 24

Describe the direction in which the cephalic portion of the linear heart tube bends.

Answer 24

Ventrally, caudally, to the right

Question 25

Describe the direction in which the atrial/caudal portion bends.

Answer 25

Dorso-cranially and to the left

Question 26

What convergence results due to looping?

Answer 26

Convergence of inflow (venous) and outflow (Arterial) ends