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Embryology Exam III > Vascular Development > Flashcards

Flashcards in Vascular Development Deck (28)
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What are the two things hemangioblasts differentiate into?

-hematopoietic lineage
+influenced by Runx-1
+give rise to large nucleated RBCs for the first 6 weeks

-endothelial lineage
+influenced by Hoxa3


What is the primary pathway of intra embryonic hematopoiesis?

Primitive streak -> yolk sac -> liver (spleen and thymus at 5-6weeks of gestation) -> bone marrow


Yolk sac RBCs

Large nucleated


Liver RBCs

-larger than normal, non-nucleated


Liver is major producer of blood cells from week 6 through month 6. Then what happens?

-during month 6, blood cell formation switches over the bone marrow

-switch is controlled by fetal adrenal gland cortisol


What composes early embryonic hemoglobin (Gower 1)? What chromosomes are associated with this?

-2 zeta chains(chromosome 16)

-2 epsilon chains (chromosome 11)


What composes early embryonic hemoglobin (Gower 2)?

-2 alpha chains (chromosome 16)

-2 epsilon chains (chromosome 11)


What composes fetal hemoglobin?

-2 alpha chains (chromosome 16)

-2 gamma chains (chromosome 11)


What composes adult hemoglobin?

-2 alpha chains (16)

-2 beta chains (11)


What are the three mechanisms for blood vessel formation?

-coalescence in situ (vasculogenesis)
+population of angioblasts become organized into a primary capillary plexus -> dorsal aortae

-migration of angioblasts into organs

-sprouting from existing vessels (angiogenesis)
+intersegmental vessels


How does vasculogenesis work?

-recruitment of angioblasts
+appearance of VEGFR-2 on membrane surfaces
+production of VEGF-A by surrounding mesenchyme


What is sprouting?

-angiopoietin-1 + Tie-2 (receptor)

-Notch signaling pathway
+appearance of VEGFR-2 on membrane surfaces
+production of VEGF-A by surrounding mesenchyme


How is the vascular wall built?

-endothelial cells release platelet-derived growth factor
+stimulates immigration of mesenchymal cells
+release of TGF and myocardium stimulates differentiation of mesenchymal cells into smooth muscle cells


How are blood vessels differentiated?

-arterial pathway
+arteries are the first to differentiate
>initial signal pathway via Shh
>Notch leads to expression of Ephrins-B2 and inhibits Eph-B4
+signaling pathway involves Shh and Notch


What ligands are expressed in developing arteries and veins?

Arteries -> Ephrins-B2

Veins -> Eph-B4


How are veins differentiated?

-initiated via transcription factor COUP-TFII
+inhibits arterial pathway by inhibiting Notch


Differentiation of lymphatics

-branch off veins
+require Sox-18 followed by Prox-1


Dorsal aorta

-paired cranially due to lack of expression of noggin and chordin by notochord


What is. The basic vertebral aortic arch pattern?

-six pairs of aortic arches, one pair per bronchial arch

-aortic arches connect ventral aorta to paired dorsal aorta


What is the aortic arch pattern in mammalian embryos?

-1st and 2nd pairs of aortic arches form but later degenerate
-3rd pair form internal carotids
-common carotids are derived from the ventral aortae between the 3rd and 4th aortic arches
-right 4th aortic arch forms the right subclavian artery
-left 4th arch form the aortic arch
-5th pair of arches degenerate
-6th pair of arches become associated with the pulmonary system


What is included in the dorsal intersegmentals?

-cervical, thoracic (intercostals), lumbar intersegmentals


-iliac arteries


What is included in the lateral intersegmentals?

-mesonephric arteries

-adrenal arteries

-renal arteries

-gonadal arteries


What is included in ventral intersegmentals?

-vitelline vessels
+celiac artery
+superior/inferior mesenterics

-allantoic vessels
+umbilical arteries


What are the pairs of cardinal veins?

-anterior, posterior, common

*anterior and posterior pairs of Cardinal veins empty into the paired common cardinals, which empty into the sinus venosus


What is the fate of the anterior Cardinal veins?

-anterior cardinals form the internal jugulars

-connection between the two is the left brachiocephalic vein

-all blood from the head is shunted to the right and drained into the right Cardinal vein -> superior vena cava


What are the additional Cardinal veins?




How is the inferior vena cava formed?

-the inferior vena cava is built as a patchwork quilt asymmetrically from remnants of the following
+vitelline vein


What are hemangioblasts?

-originate from posterolateral mesoderm during gastrulation

-organize into blood islands in yolk sac around day 18


-seed sites of intra embryonic hematopoiesis