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EMBRYO SQ 13-14 FULL.docx

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BIOL 303
Dragana Miskovic

BIOL 303 Study questions for Lecture 13, 14 – Aaron 1. What are somato- and splanchnopleure and which germ layers are involved in their formation? L13 S8 - Somatopleure – membrane wall (parietal), made of somatic mesoderm and ectoderm o Close to epidermis, - Splanchopleure – organ membrane (visceral), made of mesoderm and endoderm o Closet endodermal structures - Pleure are result of lateral mesoderm splitting o Forms pleure on top of and below a space that will form coelom 2. What is going to be formed from somatic mesoderm? L13 S10 - Limb bud - Parietal serosa (line walls of cavities) - Dermis of ventral body region - Connective tissue of limbs (bones, joints, ligaments) 3. What is going to be formed from splanchnic mesoderm? L13 S10 a. Wall of digestive and respiratory tract (except epithelial lining) b. Visceral serosa c. Heart d. Blood vessels 4. What are presumptive heart cells? What is cardiogenic mesoderm? L13S12,13 a. Presumptive heart cells i. Undetermined from splanchic mesoderm ii. Originate from two patch of epiblast close to anterior primitive streak, migrate through streak iii. Form two group mesodermal cells at level of Hensen Node in splanchic mesoderm 1. Result in two cardiogenic field on each side body > cardiogenic mesoderm (2 regions of splanchic mesoderm) a. Cardiogenic fields contain presumptive heart cells b. Cardiogenic mesoderm – the two cardiogenic fields on each side of body i. Has precursors of all 3 cells types contributing to endocardium (atrial) and myocardium (ventricular) 1. Differentiate into a. Atrial and ventricular myocyte b. Cushion cells for valves c. Purkinje conducting fibres (further diff ventricular myocyte d. Endothelial lining 1 BIOL 303 Study questions for Lecture 13, 14 – Aaron 5. What is the role of Wnts and BMPs in the specification of Heart precursor cells? S14,15 a. BMP – expressed in centre of embryo i. Specify heart precursor cells to become cardiogenic mesoderm and hemangiogenic mesoderm (heart itself) ii. Inhibited by Noggin (From notochord) iii. HEART = BMP + WNT INHIBITOR b. Wnts i. From neural tube ii. Induce/promote blood vessel formation in posterior from heart precursors w/ BMP iii. Inhibit heart formation in anterior iv. Wnt inhibitor of anterior mesoderm prevent Wnt activity in anterior mesoderm so heart formation occurs in anterior 6. What is the role of endoderm in the migration of the cardiac precursor cells? Give one example. ON EXAM S16, 17 a. The endoderm controls the direction of movement of presumptive heart cells anterior migration by releasing signals to direct the heart’s final location b. Example – Cardiac Bifida – infolding of gut movement prevented and mutated endo proteins i. Endoderm express “miles apart” protein which directs cardiac precursor cells migration so that they can fuse 1. Mutation result in no movement of cells = no fusion = two hearts formed on each side of body ii. Foxp4 protein that is expressed in endoderm is transcription factor responsible for fusion of two heart primordia 7. List three factors involved in specification of mesodermal cells into cardioblasts and two factors involved in cardioblasts’ determination into cardiomyocytes. S14,15,18, p452,447 a. Factors for specification mesodermal -> cardioblast i. Wnt ii. BMP iii. Fgf b. Factors for determination cardioblast -> cardiomyocyte (induce heart-specific proteins) i. Nkx2-5 ii. GATA 2 BIOL 303 Study questions for Lecture 13, 14 – Aaron 8. What is achieved by the looping of the cardiac tube? S21 a. Looping converts anterior-posterior polarity into right-left polarity which is present in adults i. Specifies atria and ventricles, allows atria to remain on top of ventricles 9. Define hemangioblast, pluripotent HSC and angioblast. S25 a. Hemangioblast – originate from splanchic mesoderm, common precursor to i. Angioblast – endothelial cell precursor (blood vessel cells) ii. pluripotent hematopoietic stem cell - lymphocyte stem cell, all blood cells precursor b. pluripotent hematopoietic stem cell – precursor to blood stem cell and all lineages of blood cells 10. What is the difference between vasculogenesis and angiogenesis? Where does vasculogenesis occur? S28 a. Vasculogenesis – creation of primary network of blood vessels from lateral plate mesoderm i. occur in blood islands (formed by hemangioblasts) of yolk sac (extraembryonic vasculogenesis) ii. Occur in embryo itself (intraembryonic vasculogenesis) b. Angiogenesis – remodelling of primary network into capillary bed, arteries, veins, occurs constantly 11. Describe briefly extraembryonic vasculogenesis. P459, S31 a. Blood islands form in yolk which form hemangioblast cord to give rise to early red blood cells and vasculature (multipotent cardiac precursors) needed to feed embryo i. Capillary network form (transport nutrients, blood to new heart) ii. Outer cells become flat endothelium (line blood vessel) iii. Inner cells become primordial blood 1. Differentiation depend on notch (less notch = endothelial cell) 3 BIOL 303 Study questions for Lecture 13, 14 – Aaron 12. Describe briefly intraembryonic vasculogenesis. P459, S32 a. Blood vessels created from beginning of lateral plate mesoderm b. Cords of splanchic mesodermal cells clump along future course of developing vessel i. Cells form hollowed-out tubes (made of and lined by epithelial cells) and blood cells c. PROCESS d. Splanchic mesoderm -> hemangioblast -> blood island e. Inner cells -> HSC -> blood cells f. Outer cells -> angioblasts -> endothelial cells g. Mediated by fgf, vegf, angiopoietins 13. What are the two theories about possible vascular tube lumen formation? Use diagrams. a. Cord hollowing model – membrane of all cells is part of lumen i. Endocytosis creates vacuoles
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