Lecture 6 (3a) Gastrulation Flashcards Preview

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Flashcards in Lecture 6 (3a) Gastrulation Deck (73)
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1

Cleavage

rapid mitotic divisions
- in Drosophila, only nucleus
• After cleavage = blastula
- blastoderm in Drosophila

2

Gastrulation

transforming a hollow ball into a 3-layered structure
• INVAGINATION TO FORM LAYERS

3

Germ layer

main division into cell types

4

Evtoderm makes

skin and nervous system

5

Mesoderm and endoderm make

inner structures

6

Organogenesis

different tissues and organs from

7

Metamorphosis

larval stage to maturity

8

The life of a new frog begins with the

fusion of the genetic material of the sperm and egg
(fertilization)

9

After fertilization

female frog lays eggs

10

Animal cap
(brown part)

• ectoderm in blastula
• remove = form epidermis
= some intrinsic factors that specify genes
• take from different regions - they sort themselves, reconstruct themselves

11

The first process after fertilization

CLEAVAGE
eg 2-cell embryo to 8-cell embryo

12

Somite

lateral mesoderm to spinal cord forms muscles and vertebrae

13

Cleavage results in formation of the

blastula

14

The blastula is a

hollow ball

15

Cavity in the blastula is called a

blastocell

16

Gastrulation begins with the formation of a

slit in the future dorsal side of the embryo

17

After gastrulation

organs and tissues are formed
• eg neural groove (to become neural tube)

18

The cells that generate the 3 germ layers are

present in the late blastula

19

Mid-blastula transition

• shortly before gastrulation
• transcription is activated in the embryo

20

Both endoderm and ectoderm are specified by

maternal cell fate determinants
• animal half expresses maternal factor ENDODERMIN
+ zygotic factor FOX1E
• vegetal half expresses maternal factor VEGT
+zygotic factor NODAL (mesodermal induction)

21

Explants from animal cap form

ectodermal derivatives

22

Explants from vegetal cells form

endodermal derivatives

23

Explants from animal cap and vegetal cells form ectoderm and endoderm derivatives

AUTONOMOUSLY

24

Germ layer cells reconstruct their spatial relationship

after dissociation

25

In Xenopus, endoderm development is initiated by the maternal transcription factors

VegT and Veg1

26

VegT and Veg1 found in

endoderm

27

One maternal factor activates a cascade of

embryonic genes
VEGT ACTIVATES THE EXPRESSION OF MANY ZYGOTIC TRANSCRIPTION FACTORS

28

These transcription factors factors regulate each other and there expression is maintained by

Nodal

29

Nodal

• activated by VegT
• is a morphogen, especially in future dorsal and lower concentration to ventral

30

Nodal is a morphogen and accumulates in the

endoderm