cardiogenesis Flashcards
where are Cardiac precursor cells found and what do they form
BILATERAL POPULATIONS of cells around the midline. they then migrate to the midline and fuse to form the HEART TUBE
what is heart looping
Heart tube undergoes an asymmetric bending morphogenesis
what is the origin of heart cells
constructed from two populations of cardiac cells which are specified early during development, and exhibit distinct spatiotemporal differentiation into the heart: FIRST HEART FIELD (FHF) –
SECOND HEART FIELD (SHF)
what does the first heart feild specify into
left ventricle, left and right atria
what does the second heart field specify into
right ventricle, left and right atria, outflow tract
in mice what are cardiac cells specified from
Cardiac cells are specified from mesodermal tissue along the primitive streak
in fish what are cardiac cells specified from
embryonic margin– controlled by combinatorial morphogen signalling
what does notch inhibit
Notch inhibits Tbx20 in the Chambers
what does Bmp activate
Bmp activates Tbx2 in Atrioventricular canal
what do Tbx2 -/- mice have
Tbx2 -/- mice have abnormal valve morphology and Nppa expression
what do Tbx20 -/- mice exhibit
Tbx20 -/- mice exhibit a loss of chamber identity, and an expansion of valve markers (Tbx2) Singh et al, Development
what key steps occur in Heart looping morphogenesis
- Changes in cell shape
- Growth of the heart tube
- Asymmetric cell movements at the poles of the heart
- Regional changes in ECM composition
- Lateralised cell signaling from the embryo
what helps promote looping morphogenesis
•Growth of the heart through SHF addition helps promote looping morphogenesis
where is Islet1 expressed
it is expressed in the mesoderm adjacent to the heart
Islet-1 mutant mice shows:
the heart is reduced in size and is incompletely looped
what is heterotaxia
L/R asymmetry abnormalities) often have congenital heart defects
where is nodal expressed
Nodal is asymmetrically expressed in the left lateral plate mesoderm of embryos prior to organ formation
what does loss of Nodal function results in
disrupted organ asymmetry
in zebrafish what is spaw?
In zebrafish, spaw is a Nodal homolog
what causes a higher concentration of calcium on the left side of the embryo
- A transient cup-shaped organ which forms during early somitogenesis at the posterior of the embryo
- Lined with motile cilia, which beat in a clockwise movement
- Creates a directional fluid flow
where are nodal target genes expressed
in the left half of the cardiac disc
