Heart development Flashcards
When does hematopoesis and blood vessel formation begin and where?
- Day 17 blood islands in the yolk sac form
- hemangioblasts differentiatte forming hematopoietic progenitor and endothelial precursor cells which organize to orm blood islands
What do hematopoietic stem cells differentiate into and populate?
- embryonic erythrocytes and macrophages
- early hematopoietic cells populate the liver at day 23
What are definitive hematopoietic stem cells and where are they found
- They are programmed from hemogenic endothelial cells
- found in aortic gonadal mesonephric region (AGM)
- AGM hemogenic endothelial cells appear at day 27 and appear in liver by 30 and dissapear from AGM by day 40
Where does programming of the HSCs occur and what do they generate and populate?
- Liver and this allows them to generate the full all of the myeloid and lymphoid cell lineages
- Populate lymph organs and bone marrow
Sites of hematopoesis in order from beginning to end?
- Yolk sac mesoderm starts day 17 finishes 60, source early RBC and macro
- Liver primordia colonized by primitive HSCs day 23
- AGM dorsal aorta begins forming hemogenic endothelial cells days 27-40 to populate liver
- Liver produces definitive HSC begining 5 weeks and goes until birth
- Definitive HSCs seed lymph organs and bone marrow beginning at 10.5 weeks bone marrow becomes the major hematopoetic organ
when does intraembryonic vasculogenesis start?
day 18
what is an angioma? What are capillary hemangiomas and cavernous hemangiomas?
- Abnormal BV and lymphatic capillary growth via vasculogenesis
- Capilllary hemangioma
- excessive form of capillaries
- Cavernous hemangioma
- excessive formation of venouos sinuses
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- excessive formation of venouos sinuses
What are the first signs of first heart field formation?
- Formation of EPCs clusters arranged in a horse shoe shape within a cardiogenic area of intraembryonic splanchnic mesoderm
How are primitive endocardial tubes formed?
- Anterior and posterior body folding occurs the primary heart field and coelom get folded under the embryo which pulls endoderm inside forergut
- The EPCs differentiate into endothelial cells forming primitive endocardial tubes
What does the primary heart tube wall consist of?
- Endocardium: inner epi continuous with blood vessels
- Myocardium
- Cardiac jelly: concentration of ECM btw endocardium and myocardium
What is the sinus venosus?
- made of partially confluent right and left sinus horns that receives blood from umbilical vein, vitelline vein, and common cardial vein
Where does the primitive atrium receive blood from?
Sinus venous
what separates the primitive right and left ventricles?
interventricular sulcus
What is the aortic sac or root?
- common confluens of pharyngeal arch blood vessels that contributes to great vessels
What is the first major step required for cardiac septation?
- Cardiac looping
- the atrium moves cranially and dorsally, outflow tract bends right, and ventricle bends left and superior dorsal to outflow tract.
- Initial outflow tract forms right vent
What is necessary for cardiac looping to occur?
- Secondary heart field which is found at both ends of rupturing dorsal mesocardium