Development of Cardiovascular system

Dr.G.PrabavathyAssistant Professor

Objectives

Formation of the trilaminar embryo Origin of cardiogenic cells Formation of bilateral heart fields Formation of the heart tube Folding of the heart tube Looping of the heart tube Cardiac developmental abnormalities

Day 0 : Fertilisation forming zygote initiating embryogenesis

2 cell stage; 4 cell stage; morula

Week 1 : implantation ( as a blastocyst)

Week 2 : bilaminar stage (epiblast,hypoblast)

Week 3 : gastrulation ;primitive streak,notochord and neural plate begin to form

Week 4: heart begins to form

Cardiovascular system – develops from mesoderm

Specifically, splanchnic lateral plate mesoderm

The cardiogenic field is established in the mesoderm just after gastrulation (~18-19 days) and develops into a fully functional,

multi-chambered heart by the 8th weekangiogenic cell clusters (angioblasts/hemangioblasts)

(right dorsal aorta)(right endocardial tube)

blood islands (developing blood vessels)

cardiogenic field

pericardial cavity

Langman’s fig 12-1

Cardiogenic area- cranial end between septum transversum and prochordal plate

• Intraembryonic coelom – pericardial cavity• Splanchnopleuric mesoderm underneath pericardial

cavity – Primitive heart tube

• Heart tube – endocardium of heart• Splanchnic mesoderm – myocardium and

Epicardium

After folding

Cardiogenic cords get canalized to form two endothelial heart tubes

PARTS OF THE HEART TUBE

Arterial end:

• Truncus Arteriosus – continuous with aortic sac having right and left horns

• Each horn – first pharyngeal arch artery arises,

- Continuous with respective dorsal aorta

Venous end:

Sinus venosusReceives three primitive veins:• Vitelline vein – yolk sac

• Umbilical vein – placenta

• Common cardinal vein – body wall

EMBRYONIC DILATATION ADULT DERIVATIVES

Truncus arteriosus Ascending Aorta and Pulmonary trunk.

Bulbus cordis.

.

Smooth part of Right Smooth part of Left ventricle(aortic vestibule)

Primitive ventricle Trabeculated part of Right ventricle.and Trabeculated part of Left ventricle

Primitive Atrium Trabeculated part of Right atrium Left Trabeculated part of atrium

Sinus venosus Smooth part of Right atrium(sinus venarum) coronary sinus oblique vein of the Left atrium

FATE OF VARIOUS DILATATIONS OF HEART TUBE

• Heart tube lies in the floor of pericardial cavity

After head fold, undergoes 180 rotation, heart tube lie on the roof of pericardial cavity

Moore & Persaud fig 13-9

Positioning of Heart tube in relation to pericardial cavity

Formation of Cardiac wall

• Endocardium– endothelial heart tube

• Myocardium-myoepicardial mantle

• Epicardium-myoepicardial mantle

External adult form of heart

Cardiac loop

Dorsal mesocardium

Bulboventricular loop

DEXTRO CARDIA

• All the chambers of the heart and associated blood vessels are reversed as a mirror image

• Heart tube bends to left

• Associated with situs inversus

Clinical correlation

ECTOPIA CORDIS

• rare condition in which is Heart is exposed on the surface of the Thorax.

• Due to nonunion of two pieces of developing sternum.

Single lumen primitive heart tube is partitioned into Four chambers by the formation of four septa:

1.Atrioventricular septum.

2. Interatrial septum. 3. Interventricular septum. 4. Aorticopulmonary septum

Development of various chambers of Heart

Formation of Atrio-ventricular septum• AV septum divides the AV canal into right and left AV canal• Two thickenings appear – one on dorsal and one on ventral

wall – endocardial cushions or AV cushions