Early Embryogenesis & Morphogenesis

Question 1

What is the morula

Answer 1

8-32 cells within the zona pellucida

Question 2

what are gametes derived from

Answer 2

germ cells

Question 3

what happens to the cell cycle during gametogenesis

Answer 3

slows, becomes asynchronous & cell movement begins

Question 4

Contents of … is high in the Animal pole of oocytes

Answer 4

most mRNAs, ribosomes, tRNAs

Question 5

Contents of … is high in the vegetal pole of xenopus oocytes

Answer 5

veg 1 mRNA, yolk

Question 6

What is released from the acrosome

Answer 6

digestive enzymes

Question 7

What are the blocks to polyspermy

Answer 7

change in membrane potential, cortical reaction, hyaline & fertilisation layers

Question 8

What is a fast block to polyspermy

Answer 8

change in membrane potential

Question 9

What is a slow block to polyspermy

Answer 9

cortical reaction

Question 10

What is a blastocoel

Answer 10

cells packed around a fluid filled cavity

Question 11

what is radial cleavage

Answer 11

type of holoblastic cleavage

Question 12

What symmetry is exhibited by radial cleaveage

Answer 12

symmetry

Question 13

What is tangential cleavage

Answer 13

asymmetric holoblastic cleavage

Question 14

What are the three germ layers

Answer 14

ectoderm, mesoderm & endoderm

Question 15

What does ectoderm give rise to

Answer 15

epidermis, placodes, glia, neurons, neural crest

Question 16

What does the meosderm give rise to

Answer 16

blood, kidney, heart, cartilage, skeletal muscle, dermis

Question 17

What does the endoderm give rise to

Answer 17

gut & associated organs, yolk, lungs, liver, pancreas

Question 18

What is the inner ear derived from

Answer 18

ectodermal sensory placodes

Question 19

What is the archenteron

Answer 19

embryonic gut cavity

Question 20

describe epithelium

Answer 20

highly organised, ordered, stuck together by junctional complexes

Question 21

describe epiboly

Answer 21

thinning and spreading of epithelial sheet

Question 22

What is epiboly characteristic of

Answer 22

ectoderm in some animals

Question 23

What generates lateral line organs

Answer 23

migratory movement to sensory organs

Question 24

What is created from gastrulation

Answer 24

triphoblast, gut and AP, DV axis

Question 25

Describe the process of gastrulation

Answer 25

movement of endoderm and mesoderm inside the embryo

Question 26

What movements do the germ layers undergo in xenopus

Answer 26

ectoderm - epiboly
endoderm - involution
mesoderm - convergent extension

Question 27

What are mesenchyme

Answer 27

looser meshwork of epithelium

Question 28

What is the effect of epiboly

Answer 28

increase surface area

Question 29

What model organism exhibits involution

Answer 29

xenopus

Question 30

what is involution

Answer 30

cells fold and bend aroudn blastopore

Question 31

What model organism exhibits invagination

Answer 31

sea urchin

Question 32

What is an example of invagination

Answer 32

endoderm moves up inside

Question 33

What model organism exhibits epiboly

Answer 33

danio rerio

Question 34

Describe convergent extension

Answer 34

convergence of cells that allows extension

Question 35

What is an example of convergent extension

Answer 35

xenopus - tail of tadpole

Question 36

What forces drive cell & tissue rearrangement

Answer 36

cell shape changes, proliferation, death & changes in expression of cell surface proteins

Question 37

What cell movements continue after gastrulation

Answer 37

neurulation, neural crest, germ cells migratory primordia

Question 38

What is the neural crest precursors of

Answer 38

pigment cells and enteric nervous system

Question 39

What do migratory primordia sense in danio rerio

Answer 39

water movement