day 15
Frontal view of the cardiac crescent stage of cardiac morphogenesis. In the primitive plate, bilateral fields of cardiac mesoderm are present. Part of the mesoderm layer gives rise to the cardiogenic fields, located on both sides of the midline (dashed line). The cardiogenic fields consist of a first (FHF) and second (SHF) heart fields. The two sides of the cardiac crescent fuse along the midline to form the primitive heart tube.
day21
Frontal view of the primitive heart tube stag
e of cardiac morphogenesis. Once the primitive heart tube is formed, a primitive venous pole on one end and an arterial pole on the other end are seen. Primitive regions along the heart tube include from caudal to rostral: sinus venosus, primitive atria, primitive ventricle, bulbus cordis (conus), and truncus arteriosus. The regions are separated by so-called transitional zones, which will later form the septa and valves. Two transitional zones are identifiable in this schematic: the atrioventricular ring (AVR) forming the future atrioventricular valves and the primary fold (PF) forming the future interventricular septum.
day23
Frontal view of the heart tube during the cardiac looping stage of cardiac morphogenesis. The heart tube starts to grow and contract in a pulsatile manner. At this stage, the cardiac tube starts to loop with folding along the long axis and rotation to the right and ventral, resulting in a D-looped heart. During this looping, the primitive ventricle is pushed downward and to the right while the atria move upward and posterior to the ventricles (curved arrows). As the tubular heart elongates, it bends on itself, forming an S-shaped heart. Primitive cardiac chambers are better identified and are separated by transitional zones as the sinoatrial ring (SAR), the atrioventricular ring (AVR), and the primary fold (PF).
Frontal view of the heart tube during the cardiac looping stage of cardiac morphogenesis. The heart tube starts to grow and contract in a pulsatile manner. At this stage, the cardiac tube starts to loop with folding along the long axis and rotation to the right and ventral, resulting in a D-looped heart. During this looping, the primitive ventricle is pushed downward and to the right while the atria move upward and posterior to the ventricles (curved arrows). As the tubular heart elongates, it bends on itself, forming an S-shaped heart. Primitive cardiac chambers are better identified and are separated by transitional zones as the sinoatrial ring (SAR), the atrioventricular ring (AVR), and the primary fold (PF).
Embryo Folding
This animation shows folding of the embryonic disc beginning week 3 of development.
Embryonic disc (midline section) shown to the left and early placenta to the right. The embryonic disc dorsal (ectoderm) top and ventral (endoderm) bottom. Cranial end of disc to the left and caudal end of disc to the right.
Note also the early cardiac region shown at the cranial end of disc and the allantois at the caudal end of disc extending into the connecting stalk.
Folding of the embryonic disc
1. brings the cardiac region and allantois ventrally
2. brings the buccopharyngeal membrane, cloacal membrane and connecting stalk ventrally
3. encloses the embryo in amniotic cavity
4. narrows the connection between yolk sac and midgut of the gastrointestinal tract to a channel, the yolk stalk or vitelline duct
blue - epiblast layer of amniotic cavity
yellow - endoderm layer of the yolk sac and gastrointestinal tract
red - outside embryo extraembryonic mesoderm and inside embryo mesoderm
동영상으로 배우는 태아 심장 발생학
Heart Looping (GA7 week )
Cardiac Looping
Cardiac looping occurs in humans from late in the fourth week to early in the fifth week (GA week 7).
The heart tube is initially straight in an almost rostro-caudal (head-tail) direction) virtually fixed at the upper and lower ends.
As the heart tube is grows and elongates it begins to fold or "loop" inside the pericardial cavity.
Heart Realign
Animation showing the shift in ventricle alignment relative to outflow tract.
Left and right atria shown in white at back of current view
Atrial Septation
Animation showing the complex process in forming the division between the left and right heart atria, the atrial septum.
In humans, this complex process commences in week 5 (GA week 7) and septation is not completed until after birth.
Blue - septum primum
Green - septum secundum
Red - blood flow
day 28
Heart Outflow Septation
green - right bulbar ridge(오른쪽 심장 팽대능선)
yellow - left bulbar ridge
(발생 41일 ~ 7주말)
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