Embryology Flashcards by Lor L

When does the Vascular system start to form?

In the middle of the Third Week

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Where do Progenitor Heart cells lie?

EPIBLAST- immediately adjacent to the cranial end of the primitive streak.

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What structures derive from the Primary Heart Field(PMF)?

The atria
Left ventricle
Most of the right ventricle

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What structure derives from Secondary Heart Fields(SHF)?

Part of the right ventricle
Outflow tract (conus cordis and truncus arteriosus)

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When is the Primary Heart Field formed?

Days 16-18

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When is the Secondary Heart Field formed?

Days 20-21

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What is the master gene of left-sidedness?

PITX2

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What substance results in the expression of PITX2?

Serotonin ( 5HT)

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What is the laterality pathway ?

This pathway specifies the left side of the body and also programs heart cells in the primary and SHFs

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Where is the laterality pathway expressed?

The pathway is expressed in lateral plate mesoderm on the left side.

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Where does the Secondary Heart Field reside?

The splanchnic mesoderm posterior to the pharynx

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What heart defects can arise as a result of a disruption in the laterality pathway?

*Dextrocardia (right -sided heart)
*Ventricular Septal Defects(VSD’s)
*Atrial Septal Defects ( ASD’s)
*Double outlet right ventricle ( DORV- both aorta and pulmonary artery exit via the left ventricle)
*Outflow tract defects

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What substance is the cardiac - jelly rich in?

Hyaluronic acid

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What is the function of the Cardiac Jelly?

It separates the myocardium from the endocardium

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Which layer of the heart is responsible for the formation of the coronary arteries , including their endothelial lining & smooth muscle?

The Epicardium or Visceral pericardium

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What is the lengthening process?

This lengthening process is essential for normal formation of part of the right ventricle and the outflow tract region and for the looping process.

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What issues can develop as a defect in the lengthening process?

DORV (both the aorta and pulmonary artery arise from the right ventricle)
VSD’s
Tetralogy of Fallot
Pulmonary atresia
Pulmonary stenosis

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Fill in the blanks.”The Secondary heart field (SHF) is regulated by _____?

Neural crest cells that control concentrations of FGFs in the area

When does the cardiac tube begin to bend?

Day 23

When is the cardiac loop completed?

Day 28

What is the name of the structure which connects the common atrium and the early embryonic ventricle?

Atrioventricular canal

What are the structures arises from the proximal third portion of the bulbus cordis?

Trabeculated part of the right ventricle

Fill in the blanks. The _____ of the bulbus cordis will form the will form the outflow tracts of both ventricle.

The id portion

What structures raised from the distal part of the bulbus corids?

Truncus arteriosus

What structures do the truncus arteriosus form?

Pulmonary Trunk Arch of the aorta

True or False?The junction between the ventricle and the bulbus cordis, externally indicated by bulboventricular sulcus remains narrow. It is then called the secondary interventricular foramen.

FALSE!! It is called the PRIMARY/ PRIMITIVE Interventricular foramen.

What is an example of a abnormality formed by Cardiac looping?

Dextrocardia ( Heart lies on right side instead of left side of thorax)

Which proteins secreted by the neural tube normally inhibit heart development?

WNT proteins(3a and 8)

When is the major septa of the heart formed?

27th and 37th days of development

What structures are formed from the endocardial cushions?

Atrial and ventricular ( membranous part) Septa The atrioventricular canals The valves Aortic and pulmonary channels

What is the openingbetween the lower rim of the septum primum and the endocardial cushions called?

Ostium primum

When does the Intraventricular Foramen close ?

At the end of the 7th week

What is the difference between the Foramen ovale and the Interventricular foramen?

Foramen ovale allowed for bloodflow between the right and left ATRIUM Interverntricular foramen allowed for blood flow between the right and left VENTRICLES.

What is the adult remnant of the Foramen ovale?

Fossa ovalis

Fill in the blanks." Complete closure of the interventricular foramen forms ______."

The membranous part of the interventricular septum

Fill in the blank. " Each horn of the sinus venous receives blood from ____, _____ &____"

1.Vitelline or the omphalomesenteric vein 2. Umbilical vein 3. Common cardinal vein

What are the structures that remain of the left horn after the right umbilical, left vitelline vein and common cardinal vein becomes obliterated?

The Oblique vein of the left Atrium (Vein of Marshall) Coronary sinus

When is the Left common cardinal vein obliterated from the left horn?

At 10 weeks

When is the right umbilical vein and left vitelline vein obliterated from the left horn?

During the 5th week

What structure is the Superior vena cava formed from?

The right common cardinal vein

The right vitelline vein gives rise to what structure?

Inferior Vena cava

What is known as the master gene of heart development?

NKX2.5

What two substances regulate the expression of NKX2.5?

BMP & WNT(inhibition)