Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Embryology > Lecture 12 - Gastrulation and Morphogenesis > Flashcards

Lecture 12 - Gastrulation and Morphogenesis Flashcards

1
Q

Define gastrulation

A

The process by which the bilaminar embryo is transformed into one that has 3 germ layers. Each of these layers will give rise to different parts of the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three germ layers created via gastrulation derived from?

A

The epiblast proper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What will the ectoderm differentiate to become? (2)

A

Skin

Nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What will the mesoderm differentiate to become? (3)

A

Bones

Muscles

Mesenteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What will the endoderm differentiate to become? (2)

A

Lining of gut

Large glands (e.g liver and pancreas)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When does cellular movement during gastrulation occur?

A

~15 days after fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What occurs during cellular movement during gastrulation?

A

Primitive streak forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the primitive streak define?

A

The midline and caudal end of an embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between caudal and rostral?

A

Caudal - near tail end

Rostral - near front end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the formation of the primitive streak.

A

Cells in epiblast start migrating towards the midline on the caudal end of the epiblast and then downwards towards the hypoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to the primitive streak as more cells join the stream of downwards movement?

A

The movement of the primitive streak elongates rostrally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to the primitive streak when fewer cells are actively migrating?

A

The primitive streak shortens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Is the primitive streak a structure?

A

The primitive streak is not technically a structure in itself.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the formation of the three embryonic layers.

A

Endoderm: first cells to move through the primitive streak move downwards towards the hypoblast, and then sideways underneath the epiblast. This pushes the hypoblast towards the sides of the embryo and the inner wall of the blastocyst cavity/blastocoele. The first wave of cells replace the hypoblast in the embryonic disk and gives rise to the endoderm.

Mesoderm: second wave of migrating cells moves between endoderm and epiblast. Loosely packed mesoderm is known as mesenchyme.

Ectoderm: remaining epiblast is known as the ectoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

During gastrulation, the embryonic disc elongates to form a(n) _______ shape.

A

Oblong

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the name of the depression found at the rostral end?

A

Oropharyngeal membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the oropharyngeal membrane become?

A

The mouth opening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which end does the oropharyngeal membrane come from?

A

Rostral end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the name of the depression found at the caudal end?

A

The cloacal membrane

20
Q

What does the cloacal membrane become?

A

The opening of the anus

21
Q

What end of the embryonic disc does the cloacal membrane come from?

A

The caudal end

22
Q

How many regions within the mammalian embryo contribute to establishing the head and tail ends?

A

2 - known as “centres”

23
Q

Does the oropharyngeal membrane and cloacal membrane contain mesoderm?

A

No, these structures are devoid of mesoderm.

24
Q

What is another name (or two) for a centre?

A

Organising centre

Organiser

25
Q

What is the role of an organising centre?

A

Organising centres secrete molecules that act at a distance and influence the differentiation of different body parts

26
Q

Name two examples of organisers in the embryo

A

The node of the primitive streak (primitive node)

The anterior visceral endoderm (AVE)

27
Q

What does an agonist do?

A

It initiates a response

28
Q

What does an antagonist do?

A

It inhibits a response

29
Q

What are HOX genes responsible for?

A

They encode transcription factors which regulate body formation

30
Q

What is fate mapping/lineage?

A

Understanding embryonic origin of various tissues by establishing the correspondence between cells at one stage of development and their progeny at later stages.

31
Q

What is the primitive node? What does it do?

A

An organiser that is responsible for the formation of the body, and gives rise to the notochord

32
Q

What do the AVE and primitive node contribute to?

A

The formation of an embryonic head

33
Q

What is the notochord?

A

A transient medial mesodermal structure that influences the development of surrounding tissue

34
Q

At what time do organs begin to form?

A

During the 4th week of development

35
Q

What occurs during morphogenesis?

A

The embryo undergoes dramatic changes in shape and size

36
Q

What is the overall product of embryonic folding?

A

The embryo transforms from a trilaminar disc to a 3D structure

37
Q

What is embryonic folding the result of?

A

Differential growth - some parts of the embryo grow at an increased rate relative to other parts

38
Q

Along what axis does longitudinal bending occur?

A

The rostro-caudal axis

39
Q

What is the process of longitudinal bending?

A

The flat disc of the trilaminar embryo bends along the rostro-caudal axis

The head and tail move downwards, endoderm moves towards middle

A tube formed with blind ends which will eventually become the gut

40
Q

Along what axis does transverse folding occur?

A

The transverse axis

41
Q

Describe the process of transverse folding

A

Transverse folding occurs simultaneously with longitudinal bending

The lateral edges of the embryo move downwards and eventually meet along the midline - the embryo is now tube shaped

Fusion begins at the cranial and caudal ends and progress like a zipper towards the mid-trunk

42
Q

By the end of embryonic folding, what is the shape of the embryo?

A

The embryo is a closed tube except for a small opening connecting the inside of the gut to the yolk sac

43
Q

What does the 3D structure of an embryo 1 month post-fertilisation resemble?

A

It resembles that of a typical vertebrate.

44
Q

What are characteristics of a typical vertebrate that can be seen in the embryo at the miniature vertebrate stage? (3)

A

Surrounded by ectoderm

Endoderm surrounds a hollow tube (will become walls of gut)

Mesodermal structures developing between ectoderm and endoderm

45
Q

Have the organs fully developed by the time the embryo reaches the miniature vertebrate stage?

A

No, organ formation has begun but still possesses a rudimentary structure, and will continue to develop.

Embryology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions