Morphogenesis

Question 1

During the formation of the bilaminar disc, name the cell population that lines the following cavities:
A. amniotic cavity:
B. yolk sac:

Answer 1

A. amniotic cavity: epiblast (Answer)
B. yolk sac: hypoblast (Answer)

Question 2

Question 2: The prechordal plate forms from a thickening of [x] cells and marks the future [y] end of the embryo. Fill in the blanks for [x] and [y].

Answer 2

Answer: [x] = hypoblast
[y] = cranial/rostal

Question 3

Question 3
https://canvas.qut.edu.au/courses/15043/files/2632720?module_item_id=1441295

Answer 3

Amniotic cavity

Question 4

The notochord induces the overlying ectoderm to form the:

Answer 4

neural plate

Question 5

Question 5
https://canvas.qut.edu.au/courses/15043/files/2632720?module_item_id=1441295

Answer 5

Gastrulation

Question 6

Question 6
https://canvas.qut.edu.au/courses/15043/files/2632720?module_item_id=1441295

Answer 6

Endoderm

Question 7

Which cells ingress through the primitive pit and groove to form the mesoderm and endoderm?

Answer 7

epiblastic cells

Question 8

In the absence of the primitive streak, which of the following tissues do not form?
A. ectoderm
B. mesoderm
C. endoderm
D. epiblast
E. trophoblast

Answer 8

b, c

Question 9

Order the germ cell layers from closest to amniotic cavity to furthest away in the trilaminar embryonic disc
1. mesoderm
2. ectoderm
3. endoderm

Answer 9

Outermost: ectoderm
Middle: mesoderm
Innermost: endoderm

Question 10

Which of the following statements is NOT correct concerning the notochord?
A. The notochordal process lengthens as the primitive streak regresses
B. the notochordal process is formed from ingression of epiblastic cells through primitive groove
C. notochordal process extends towards the prechordal plate
D. in the absence of the notochord, the central nervous system does not form
E. the notochord is located in the mesodermal layer

Answer 10

b

Question 11

The expression of which gene concentrates on the left side of the embryo to result in handed asymmetry?

Answer 11

Nodal

Question 12

What is the fate of the epiblast?

Answer 12

Proliferate and migrate through primitive pit and groove of primitive streak to displace hypoblast cells and become definitive endoderm

Question 13

What is the importance of the prechordal plate position?

Answer 13

Orients body axis and indicates future cranial region, important signalling centre for controlling forebrain + eyes

Question 14

What events typify gastrulation?

Answer 14

Formation of ectoderm, endoderm, mesoderm and establishment of axial orientation (bilaminar disc -> trilaminar disc)

Question 15

What is the importance of the primitive groove and pit in gastrulation?

Answer 15

the primitive groove and pit are essential structures during gastrulation as they mark the beginning of the process of germ layer formation. This process is a fundamental step in embryonic development, as it leads to the creation of the three primary germ layers and establishes the foundation for the subsequent development of the embryo’s body plan and organs.

Question 16

What is the relationship between the primitive streak and notochord?

Answer 16

the primitive streak and the notochord are intimately connected in the early stages of vertebrate development. The primitive streak serves as a critical structure during gastrulation, allowing cells to ingress and establish the germ layers, including the mesoderm. Some of these mesodermal cells go on to become the notochord, which is essential for providing structural support to the developing embryo and participating in the patterning of the body plan, particularly the vertebral column.

Question 17

What would be effect to embryological development if 2 notochords formed?

Answer 17

the presence of two notochords would disrupt the highly coordinated and precisely regulated processes of embryological development, potentially leading to a wide range of structural and functional abnormalities in the developing embryo especially in vertebral column

Question 18

What is the importance of an ‘organiser’ in embryological development? What structures have been shown to be organisers in the human embryo

Answer 18

region or group of cells that plays a pivotal role in orchestrating the development and patterning of surrounding tissues and structures. Organizers are responsible for initiating specific developmental processes and ensuring the proper formation of body structures. Organizers are best known for their role in inducing changes in cell fate, differentiation, and tissue organization in developing embryos eg notochord

Question 19

Epiblastic and mesenchymal cells are pluripotent. What does this mean? How is fate determined?

Answer 19

Epiblastic Cells: Epiblast cells are pluripotent. They are part of the early embryonic structure known as the epiblast, which is derived from the inner cell mass of the blastocyst. Epiblast cells have the potential to differentiate into cells from all three germ layers (ectoderm, mesoderm, and endoderm).

Mesenchymal Cells: Mesenchymal cells are also pluripotent. These cells are typically found within the mesoderm, one of the germ layers. Mesenchymal cells can differentiate into various mesodermal cell types, such as muscle cells, bone cells, and blood cells.

Fate determination in pluripotent cells is a complex process governed by genetic and epigenetic factors, signalling pathways, and microenvironmental cues.

Question 20

Which signalling molecule is inhibited on the right side of the body to produce handed asymmetry in the embryo? What would happen if it was inhibited on the left side? What is this condition called?

Answer 20

Lefty2 inhibits nodal and is expressed in the midline of the embryo in order to prevent any nodal moving to the right side of the embryo. If inhibited on the left side, the heart and liver would move to the right side (situs inversus totalis)

Question 21

What is functional difference between amniotic cavity and yolk sac?

Answer 21

Amniotic cavity holds embryo and protects it, yolk sac is the source of nutrients and becomes the placenta

Question 22

The primitive CNS develops in which primary germ layer?

Answer 22

Ectoderm