Heart Development Flashcards
Where do the first blood cells arise? Are these different from hematopoeitic stem cells?
First blood cells arise in blood islands on the wall of the yolk sac (mesoderm)- this population is transitory
Definitive hematopoeitic stem cells are derived from mesoderm surrounding the aorta in a site near the developing mesonephric kidney called the AGM
What is the major hematopoietic organ in the fetus from month 2-7?
Liver
Yolk sac mesoderm forms the first blood cells at day 17 and finishes by day 60. The liver primordia is colonized beginning at day _____ and continues until birth. The AGM begins hematopoietic processes at day _____ prior to contributing to liver colonization
23; 27-40
[bone marrow also hematopoietic at 10.5 weeks]
Process by which cells of the primary heart field are induced by the underlying pharyngeal endoderm to form cardiac myoblasts and blood islands that will form blood cells and vessels
Vasculogenesis
Blood cells may only belong to what lineage prior to colonization of the liver?
Myeloid
____________ = common precursor for vessel and blood cell formation that are formed in blood islands of yolk sac
Hemangioblasts
What is the difference in fate of hemangioblasts at the center of blood islands vs at the periphery?
Central hemangioblasts form hematopoietic stem cells (precursors of all blood cells)
Peripheral hemangioblasts differentiate into angioblasts (precursors to blood vessels)
______ = formation of blood vessels by sprouting from existing vessels
Angiogenesis
_____ = existing blood vessel splits into 2
Intussusception
What is the AGM region?
Aortic-gonadal-mesonephric region
Where definitive hematopoietic stem cells are programmed from hemogenic endothelial precursor cells
[hematopoietic stem cells appear at day 27 and disappear from AGM by day 40]
What is the major difference between intraembryonic vasculogenesis and extraembryonic vasculogenesis?
Intraembryonic vasculogenesis involves coupling with hematopoiesis (because it all starts with the blood islands)
All other de novo blood vessel formation occurs SEPARATE from hematopoeisis
Extraembryonic vasculogenesis begins around day 17 when extraembryonic ______ and _______ mesoderm differentiate into either hematopoietic progenitors or ___________ precursor cells. The primary function is to meet immediate need for blood cells
Splanchnic; chorionic
Endothelial
What are the 2 major mechanisms of vascular plexus expansion
Angiogenesis
Intussusception
______ are characterized by abnormal blood vessel and lymphatic capillary growth
Angiomas
What type of angioma is characterized by excessive growth of capillaries?
Capillary hemangioma
What type of angioma is characterized by excessive growth of venous sinuses?
Cavernous hemangioma
Generation of ______ _______ forms 2 bilateral primary heart fields which eventually fuse, thereby creating linear primary heart tube
Precardiac mesoderm
By day 18 of heart development, the lateral mesoderm of the primary heart tube has ______ and _______ components, and the latter will give rise to almost all heart components
Somatopleure; splanchnopleure
Early endocardial cells separate from the mesoderm to create paired heart tubes; what process occurs to bring the paired heart tubes together into a single tube?
Lateral embryonic folding
What structures eventually unite to form a horseshoe shaped endothelial lined tube surrounded by myoblasts, forming the cardiogenic region?
Blood islands
The intraembryonic cavity over the cardiogenic region of the primitive heart will later develop into what structure?
Pericardial cavity
What structures form from blood islands that appear bilaterally and close to midline of the embryonic shield?
Dorsal aortae
All heart structures come from embryonic _______ _______, except for neural crest cells which are ________
Splanchnic mesoderm; ectoderm
When does the primary heart field form
Around day 19 (range of 16-18)