lecture 2 Flashcards
what is gastrulation
the formation of anatomy and recognisation of blastula
what are the 3 layers formed in gastrulation (trilaminer plate)
ectoderm
mesoderm
endoderm
what does the ectoderm become
skin and nervous system
what does mesoderm become
muscle, bone, cartallige, connective tissue, vasculature, blood, kidney, gonads
what does endoderm become
lining of digestive tract, lungs, liver, pancreas
what are the three types of gastrulation movement of cells
invagination
involution
ingression
describe invagination
giggidy
infolding of surface epithelium of blatula from the blastopore and pushes through the centre of blastocoel
describe involution
similar to invagination- also forms archenteron. foldsback onto inner surface of blastula. uses blastula as source of migration
what is the archenteron
primitive gut
describe ingression
migration of individual cells from surface epithelium to interior of the embryo. breaks away from epithelium migrates through basal lamina. similar to mesenchymal cells
what type of egg is a sea urchin
Isolecithal holoblastic
why is a sea urchin good to study
embryo just a layer of cuboidal cells
contains protein fibres required for migration
see through
what is the first stage of sea urchin gastrulation
cells at vegetal pole elongate to form vegetal plate, apical surface constricts to form bottle cells which break contact with adjacent cells. the bottle cells ingress to form Primary mesenchymal cells
how are primary mesencymal cells formed
bottle cells ingress to form primary mesenchymal cells. they cluster at the vegetal plate. loosely packed
what is the second step of gastrulation
inward buckling of monolayer at the vegetal plate
