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Developmental Biology > Phases Of Early Development > Flashcards

Phases Of Early Development Flashcards

1
Q

What occurs in the pre-organogenesis phase? (3)

A

Cell division
Polarisation of the embryo
Formation of two layers (bilaminar germ disc)

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2
Q

What happens in the embryo phase? (3)

A
  • Gastrulation
  • Laying down of basic body plan
  • organogenesis
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3
Q

What is gastrulation?

A

The blastula (single layered) is reorganised into a multilayered gastrula

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4
Q

What happens in the fetus phase? (3)

A

Growth
Refinement
Function

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5
Q

What is an oocyte?

A

Female sex cell that hasn’t undergone meiosis

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6
Q

What is an ovum?

A

A mature female sex cell

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7
Q

What is a morula?

A

A ball of cells resulting from hyperplasia of the zygote. The cell remains the same size

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8
Q

What is a zygote?

A

A fertilised ovum. It has both sets of nuclei

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9
Q

What is compaction?

A

When the morula compacts into a tight ball of cells

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10
Q

What is a blastomere?

A

A cell that makes up the morula

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11
Q

What is a blastocyst?

A

A hollow ball of cells with a thickening at one end

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12
Q

What is a blastocoel?

A

The fluid inside the blastocyst

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13
Q

List the phases of zygote division

A

Zygote-two stage cell- four stage cell- morula(8)-blastocyst-loss of zona pellucida

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14
Q

What are the two components of a blastocyst?

A

Trophoblast and embryoblast

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15
Q

The inner cell mass of the blastocyst separates into two layers. Name the layers

A

Epiblast and hypoblast

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16
Q

What will the epiblast form?

A

The embryonic tissue

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17
Q

What will the hypoblast form?

A

Embryonic tissues

18
Q

What do the extra-embryonic membranes do/provide?

A

Nourishment
Protection
Waste disposal

19
Q

What do the extraembryonic membranes consist of? (4)

A

Amnion
Allantois
Chorion
Placenta

20
Q

What is the amnion?

A

It protects the embryo allowing it to float

21
Q

What is the allantois for?

A

Fetal waste disposal

22
Q

What does the chorion do?

A

It contains the blood vessels for exchange with the external environment

23
Q

What is the placenta and what is it formed from?

A

It is an organ that contains maternal and fetal blood vessels. It is made from the cytotrophoblast and the syncytiotrophoblast

24
Q

What week does preorganogenesis happen?

A

0-2

25
Q

What weeks does the embryonic phase occur?

A

3-8 weeks

26
Q

What weeks does the fetal phase occur?

A

9-38

27
Q

Gastrulation forms three body layers, name these

A

Ectoderm
Mesoderm
Endoderm

28
Q

Which layer is the ectoderm and what will it form?

A

Outer layer

Skin and nervous system

29
Q

What layer is the mesoderm and what will it form?

A

Middle layer

Internal organs and chorion

30
Q

What layer is the endoderm and what will it form?

A

Inner layer

Internal linings

31
Q

At how many days does Gastrulation occur?

A

12-15

32
Q

At how many days post fertilisation is the embryo not allowed to be used?

A

14

33
Q

What is the primitive streak?

A

Is the first thing to form in Gastrulation, it is on the surface of the epiblast-a line at one end. At the end the primitive node forms

34
Q

What is invagination?

A

The cells of the epiblast migrate to the primitive streak and slip beneath it via the node

35
Q

How are the three layers formed by invagination?

A

The cells move and displace the hypoblast

36
Q

What is the germ layer?

A

The ectoderm

37
Q

What is a key part formed by Gastrulation?

A

Gut formation

38
Q

What layer rolls and pinches off forming the gut?

A

The endoderm

39
Q

What would happen if there were problems with the Gastrulation phase?

A

Pregnancy would normally terminate

40
Q

What is the disorder situs inversus?

A

Where the position of the internal organs are reversed

41
Q

What is situs ambiguous disorder?

A

Where so,e of the internal organs are displaced

42
Q

What is a sacrococcygeal teratomas?

A

A tumour in baby which has all three layers of Gastrulation, often highly vascularised

Developmental Biology (4 decks)

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