Early Embryogenesis & Morphogenesis Flashcards
What is the morula
8-32 cells within the zona pellucida
what are gametes derived from
germ cells
what happens to the cell cycle during gametogenesis
slows, becomes asynchronous & cell movement begins
Contents of … is high in the Animal pole of oocytes
most mRNAs, ribosomes, tRNAs
Contents of … is high in the vegetal pole of xenopus oocytes
veg 1 mRNA, yolk
What is released from the acrosome
digestive enzymes
What are the blocks to polyspermy
change in membrane potential, cortical reaction, hyaline & fertilisation layers
What is a fast block to polyspermy
change in membrane potential
What is a slow block to polyspermy
cortical reaction
What is a blastocoel
cells packed around a fluid filled cavity
what is radial cleavage
type of holoblastic cleavage
What symmetry is exhibited by radial cleaveage
symmetry
What is tangential cleavage
asymmetric holoblastic cleavage
What are the three germ layers
ectoderm, mesoderm & endoderm
What does ectoderm give rise to
epidermis, placodes, glia, neurons, neural crest
What does the meosderm give rise to
blood, kidney, heart, cartilage, skeletal muscle, dermis
What does the endoderm give rise to
gut & associated organs, yolk, lungs, liver, pancreas
What is the inner ear derived from
ectodermal sensory placodes
What is the archenteron
embryonic gut cavity
describe epithelium
highly organised, ordered, stuck together by junctional complexes
describe epiboly
thinning and spreading of epithelial sheet
What is epiboly characteristic of
ectoderm in some animals
What generates lateral line organs
migratory movement to sensory organs
What is created from gastrulation
triphoblast, gut and AP, DV axis
Describe the process of gastrulation
movement of endoderm and mesoderm inside the embryo
What movements do the germ layers undergo in xenopus
ectoderm - epiboly
endoderm - involution
mesoderm - convergent extension
What are mesenchyme
looser meshwork of epithelium
What is the effect of epiboly
increase surface area
What model organism exhibits involution
xenopus
what is involution
cells fold and bend aroudn blastopore
What model organism exhibits invagination
sea urchin
What is an example of invagination
endoderm moves up inside
What model organism exhibits epiboly
danio rerio
Describe convergent extension
convergence of cells that allows extension
What is an example of convergent extension
xenopus - tail of tadpole
What forces drive cell & tissue rearrangement
cell shape changes, proliferation, death & changes in expression of cell surface proteins
What cell movements continue after gastrulation
neurulation, neural crest, germ cells migratory primordia
What is the neural crest precursors of
pigment cells and enteric nervous system
What do migratory primordia sense in danio rerio
water movement
