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Hormones > Embryogenesis and development 8 and 9 > Flashcards

Embryogenesis and development 8 and 9 Flashcards

1
Q

What is cleavage?

A

Cell division in early embryo

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2
Q

What is gastrulation?

A

Cell movements which produce gut and three primary germ layers

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3
Q

What is organogenesis?

A

Development of organs

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4
Q

Describe the features of sea urchin cleavage

A

Rapid divisions
Bastomeres all the same size
Holoblastic cleavage (division of whole cell)
Blastomeres become smaller with each division

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5
Q

What is unequal holoblastic division?

A

Blastomeres in animal pole are
smaller than blastomeres in
vegetal pole because of presence
of yolk in vegetal hemisphere.

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6
Q

When does unequal holoblastic division take place?

A

In amphibian cleavage

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7
Q

What is mesoblastic cleavage?

A

Cleavage plane does not direct yolk

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8
Q

What comes after the cleavage stage in chicks?

A

Blastula formation

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9
Q

What do we refer to cells as in embryogenesis?

A

Blastomeres

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10
Q

What is holoblastic division?

A

Cleavage plane divides the blastomere completely

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11
Q

What is a morula?

A

After several cleavage divisions, the small sold ball of blastomeres that form

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12
Q

Why are blastosomes the same size in sea urines?

A

There is no yolk in sea urine eggs

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13
Q

Does the amphibian egg contain lots of yolk?

A

Yes

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14
Q

What is the top pigmented half of the amphibian egg called?

A

Animal pole

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15
Q

Whats is the unpigmented bottom half of the amphibian egg called?

A

Vegetal hemisphere

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16
Q

What happens to the cytoplasm when the sperm enters the egg in amphibians?

A

Cytoplasm is rearranged and the cortex contracts towards the point of sperm entry revealing the grey crescent

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17
Q

What is the dorsal surface marked with in amphibians?

A

Grey crescent

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18
Q

What is the ventral surface marked with in amphibians?

A

Point of sperm entry

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19
Q

Who undergo meroblastic cleavage?

A

Chicks

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20
Q

What comes after blastula formation in chicks?

A

Gastrulation

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21
Q

Gastrulations forms which 3 germ layers in chicks?

A

Ectoderm
Mesoderm
Endoderm

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22
Q

What does the ectoderm include?

A

Epidermis of skin
Nervous system
Pituitary gland
Teeth

23
Q

What does the mesoderm include?

A

Muscular system
Skeletal system
Reporductive system
Dermis of skin

24
Q

What does the endoderm include?

A

Epithelial lining of gut, respiratory and excretory tracts

25
Q

Describe the process of gastrulation in sea urchins.

A

Cells at the vegetal pole thicken to form the vegetal plate which fold inwards forming the archenteron which form the endoderm
Mesenchyme cells migrate into the blastocoel forming the mesoderm
Cells remaining on the surface form the ectoderm

26
Q

Describe the process of gastrulation in chicks.

A

Straight invagination of the upper layer of cells of the blastoderm
Cells migrate through blastocoel displace the hydroblast cells and form the endoderm
Next cells migrate through the blastocoel to form the mesoderm
Remaining cells on top form the ectoderm

27
Q

What is a primitive streak?

A

The line of invagionation in chick gastrulation

28
Q

Describe the process of gastrulation in amphibians.

A

Tuck at a site where grey crescent is situated which is called the dorsal lip of the blastopore
The endoderm arises from cells lining the archenteron, the mesoderm arises from cells which were deep in the equator (marginal zone) and the ectoderm is derived from the cells remaining on the surface

29
Q

What do the amnion and chorion develop from in chicks?

A

Folds of ectoderm and mesoderm which extend over the top of the embryo and fuse

30
Q

What is the role of the amniotic sac in chicks?

A

Surround the embryo to protect it

31
Q

What is the amniotic sac lined with?

A

Amnion

32
Q

When is the first human cleavage?

A

24-30 hours after fertilisation

33
Q

What is formed fro the first human cleavage?

A

2 blastomeres

34
Q

When does the morula enter the uterus?

A

Day 4-5

35
Q

When does a blastocyst form during human fertilisation?

A

32 cell stage

36
Q

What does a blastocyst contain?

A

Inner cell mass
Blastocoel
Trophoblast

37
Q

What happens on the 5th day after human fertilisation?

A

Hatching: The blastocyst digests a hole in the zone pellucida and emerges

38
Q

What must occur before implantation in the uterus?

A

Hatching

39
Q

What happens during implantation?

A

Day 6-7
Blastocyst secretes enzymes to burrow unto endometrium
Inner cell mass next to the endometrium

40
Q

What happens 8 days after human fertilisation?

A

Bilaminar embryonic disc is formed where the inner cell mass has rearranged into two layers called the epiblast (upper) and the hypoblast (lower)

41
Q

Describe the primitive streak in human gastrulation

A

Forms in dorsal epiblast

Defines anterior and posterior of the embryo

42
Q

How does gastrulation in humans form the 3 germ layers?

A

It enables the production of a trilaminar embryonic disc which consists of all 3

43
Q

What do cells form the primitive node produce?

A

notochord

44
Q

How does neurulation in vertebrates occur?

A

Notochord develops from dorsal mesoderm
Induction of neural plate from ectoderm layer above the notochord
A neural groove and neural folds form from the dorsal ectoderm
The neural folds rise up, meet and fuse to form the neural tube

45
Q

What does the neural tube become?

A

CNS

46
Q

What are the first organs to develop in vertebrates?

A

Neural tube

Notochord

47
Q

What 3 components in development comprised of?

A

Growth
Morphogenesis
Differentiation

48
Q

WHAt happens in neurulation in amphibians?

A

Development of brain and spinal cord

49
Q

What is induction?

A

The fate of one cell is influenced by another

50
Q

What did the researchers do in the dorsal mesoderm experiment (1)?

A

Used two very early early newt embryos; unpigmented and pigmented. The dorsal lip of the blastopore from the unpigmented newt gastrula was transplanted
into the ventral side of the pigmented newt gastrula

51
Q

What did the researchers find in the dorsal mesoderm experiment (1)?

A

Conjoined twins produced. Second embryo produced daily pigmented tissue.

52
Q

How did the organiser alter cell fate?

A

BMP-4 is uniformly distributed in late blastula and causes VENTRAL development. Chordin and Noggin (secreted by organiser) stop action of BMP-4 and allow dorsal development e.g. muscle and notochord (dorsal mesoderm)

53
Q

Describe the induction of the neural plate(2)

A

Signalling molecules from the notochord and surrounding cells cause the overlying ectoderm to take on a neural fate

Hormones (7 decks)

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