Lecture 8 - Gastrulation Summary

Question 1

• process involving a complex series of cell shape changes and cell movements that occur in the blastula
• establish the basic body plan and creates the three primary germ layers

Answer 1

gastrulation

Question 2

three primary germ layers

Answer 2

1. ectoderm
2. mesoderm
3. endoderm

Question 3

developmental fates of ectoderm

Answer 3

1. epidermis of skin
2. nervous system
3. sense organs

Question 4

developmental fates of mesoderm

Answer 4

1. skeleton
2. muscles
3. blood vessels
4. heart
5. blood
6. gonads
7. kidneys
8. dermis of skin

Question 5

developmental fates of endoderm

Answer 5

1. lining of digestive and respiratory tracts
2. liver
3. pancreas
4. thymus
5. thyroid

Question 6

developmental fates of neural crest

Answer 6

some parts of the nervous system

Question 7

how doe cells that are tightly attached to each other via junctions move

Answer 7

as cell sheets

Question 8

different gastrulation movements

Answer 8

1. invagination
2. involution
3. delamination
4. ingression

Question 9

cell sheet dents inward

Answer 9

invagination

Question 10

cell sheet rolls inward

Answer 10

involution

Question 11

cell sheet splits in two

Answer 11

delamination

Question 12

cells break away from cell sheet and migrate as individual cell

Answer 12

ingression

Question 13

Gastrulation in sea urchins

Answer 13

1. begins with formation of vegetal plate and ingression of primary mesenchyme into blastocoel
2. remaining cells of vegetal plate invaginate into blastocoel forming the endoderm
3. cells staying at surface form ectoderm

Question 14

future mesoderm cells

Answer 14

primary mesenchyme cells

Question 15

future digestive gut

Answer 15

archenteron

Question 16

Gastrulation in frogs

Answer 16

1. cells from the animal pole involute over dorsal lip of blastopore into the blastocoel
2. cells eventually press against far wall
3. eliiminate blastocoel, producing archenteron with yolk plug
4. these movements create two layers: outer ectoderm and inner endoderm
5. mesoderm forms later in between

Question 17

Gastrulation in birds

Answer 17

1. blastula consists of disc of cells, the blastoderm, sitting atop large yolk mass
2. blastoderm delaminates into two layers with blsatocoel cavity in between
3. upper layer produces all 3 germ layers
4. cells that migrate through primitve streak from endoderm or mesoderm
5. cells that remain form ectoderm

Question 18

Gastrulation in mammals

Answer 18

1. proceeds similarly to that in birds
2. embryo develops from inner cell mass
3. ICM flattens and delaminates into 2 layers
4. primitive streak forms
5. cell movements through it give rise to 3 primary germ layers