development of heart Flashcards
why does the feotus need a criculatory system
feotus circulatory system bypasses the lungs, cannot ventilate must collect oxygen from mothers placenta
to carry nutrients, oxygenco2 as nutrients available not sustainable for growing size of feotus
when does it form this circulatory system
weeks 4-8
explain the formation of the circulatory system
there is mesoderm layer that lies around developing yolk sac- called the extra embryonic mesoderm
blood islands that are not connected to each other form in the mesoderm layer which contain stem cells that will form the embryonic blood vasculature
these spread to the rest embyro
why is the yolk sac retained
yolk sac is important for development of blood and vasculature
what do the stem cells that form vasculature and blood express
express cpeb4
where does the heart begin to form
in the chest region below the foregut
what are haemangioblasts
stem cells that can produce blood cells and endothelial cells
first step of vasculogenesis
specification of mesoderm : hemangioblasts are specified within yolk sac mesoderm (specification process
what is the second step of vasculogenesis
formation of blood islands - haemangioblasts form aggregates with haematopoeitic stem cells hsc in the centre and angioblasts on the outside (formation of blood islands)
what is the third step of vasculogenesis
haematopoetic stem cells will then produce primitive erythrocytes where angioblasts will form the endothelial cells
what is the fourth step of vasculogenesis
blood islands will increase in size and fuse with each other to form vasculature
what is the fifth step of vasculogenesis
endothelial cells organise into capillaries which then enlarge and connect to form the primary vasculature network
where does vasculogenesis occur
in the splencnic layer of the lateral plate mesoderm (gut) in the chorion
does vasculogenesis happen before angiogenesis
vasculogenesis and then angiogenesis
define angiognesis
extension of blood vessels
