Cardiovascular (embyrology) Flashcards
Where does the entire blood vascular system develop from?
Splanchnic mesoderm
Prenatal Hematopoiesis
Yolk sac and allantois splanchnic mesoderm: 4-5 wks
Liver: 6 wks to mid gestation
Spleen and thymus: 8-16 weeks
Bone marrow: 16 weeks to beyond
Which organs takes over the function of bone marrow when it’s damaged?
Liver and spleen
How many BVs are in the umbilical cord?
3: 2 umbilical arteries and 1 umbilical vein
arteries becoming lateral ligaments of the bladder
What do the vitelline veins and arteries connect?
Early heart with the yolk sac
What does the umbilical veins and arteries connect?
Early heart with the allantois and placenta
What do the cardinal veins (cranial, caudal and common) connect?
Heart with the body parts
Early blood flow
Vitelline or umbilical vein –> sinus venosus –> atrium –> ventricle –> truncus arteriosis –> aortic arches –> dorsal aorta –> vitelline artery (yolk sac) or umbilical artery (allantois)
Where does the heart develop?
Cranial to the developing embryo
How does the heart migrate?
Embryo folding migrates heart from cranial to the embryo to the pharyngeal area
Where does the yolk sac and allantois orginate?
YS: mid gut
A: outpocketing from the hind gut
Stages in Heart Development
D18: blood islands and myoblasts cr. to the neural plate
D 20-35: Fusion, division and folding of endocardial tubes and an anticlockwise turn brings atria dorsal to ventricles
Pericardial cavity (intraemryonic coelom) cr. to embryo
___________ gives rise to the pulmonary artery and aorta
Truncus arteriosus
What does the right sinus venosus form?
Overdevelops and forms smooth part of the right atrium
What does the left sinus venosus form?
Atrophies and forms coronary sinus and oblique vein of left atrium (left to right shift in circulation)
Endocardial cushion
Divides Av canal into right and left AV canals
Interartrial septa 1 & 2
Divides atria into right and left atrium
1: valve for the foramen ovale
2: foramen ovale opens in 2 and allows blood to move from right to left atrium
Interventricular septa
Divides ventricles into right and left
Foramen filled by membranous tissue from endocardial cushion and base of truncus arteriosus
What does partitioning of the truncus arteriosus involve?
Formation of spiral septum that divides the TA into:
1. Aorta that connects with l. ventricle
2. Pulmonary artery that connects with the r. ventricle
What does the failure of spiral formation (TA) do?
Reverses arrangement so the aorta is connected to the r. side and pulmonary a. is connected to the l.
Ectopic Cords
Heart located in the neck region (cattle)
Spiral Septal Defect
Small opening between the pulmonary trunk and aorta
Venous blood has direct access to aorta before going to lungs
Like patent ductus arteriosus
Interventricular Septal Defect
An opening in the membranous part of the interventricular septum (most frequent)
Caused by abnormal closure of the interventricular foramen
Dextrocardia
Mirror image heart that occurs as an isolated defect or with a complete inversus
Tetralogy of Fallot
Causes cyanosis in domestic animals and human
From failure of migration of neural crest cells in distal part of TA
Craniofacial abnormalities
What are the 4 lesions of Tetralogy of Fallot
- Interventricular septal defect
- Pulmonary stenosis
- Dextro-aorta
- Hypertrophy of r. ventricle (consequence of first 3 defects)
first 3 from abnormal partitioning of TA by spiral septum
Aortic arches
1-6 pairs
Connecting ventral aortrae with dorsal aortrae that fuse caudally
Which arches degenerate?
1, 2, 5
Arch 3
Becomes internal carotid
Dorsal aorta between 3 & 4 degenerate freeing intl carotid
Arch 4
On l. side becomes arch of aorta
R. side becomes root of subclavian
Arch 6
Left: proximal part is pulmonary artery and distal part is ductus arteriosus
Right: proximal part is pulmonary artery and distal part degenerates
What makes up the right subclavian?
Right 4th arch
Right dorsal aorta up to 7th intersegmental
7th intersegmental
What makes up the left subclavian?
7 intersegmental exclusively
Vertebral both sides
1-6 cervical intersegmental fuse proximally and degenerate distally
Remains connected to 7th intersegmental (becomes subcalvian)
Where does the right subclavian move?
Upward joining the root of common carotid (area will become the brachiocephalic trunk)
How is the subclavian in the dog and pig?
Right subclavian originates from brachiocephalic trunk
Left subclavian from arch of aorta
How is the subclavian in the horse and ox?
Both subclavians originate from the brachiocephalic trunk
Recurrent laryngeal nerves
Left: hooks around ducuts arteriosus, atrophies and become ligamentum arteriosus
Right: hooks around right subclavian
Vascular ring anomaly
Abnormal origin of the right subclavian artery (originating from arch of aorta)
Proximal part of dorsal aorta degenerates
Symptoms of vascular ring anomaly
Esophagus dilation proximal to the site of crossing
Difficulty swallowing solid food leading to regurgitation
Foramen ovale
Changes to fossa ovalis
Increased pressure in l. atrium @ birth causes fusions of septum 1 & 2
Ductus arteriosus
Atrophies and becomes ligamentum arteriosus due to increased blood oxygen, bradykinin secretion and decreased prostagladin secretion
Anomalies dealing with fetal adaptations
Interatrial septal defect
Persistent ductus arteriosus
Persistent ductus venosus leading to portosystemic shunt
Patent Ductus Arteriosus
DA fails to close @ birth
Blood shunts from aorta to pulmonary artery
Signs: continuous murmur
Portosystemic Shunt
Portal vein blood bypasses liver
Blood not detoxified leading to nervous signs and brain injury
