Embryology Parts I And II questions

Question 1

The blastocysts contain which 2 parts

Answer 1

• inner cell mass

- trophoblast

Question 2

Cells in the ICM differentiate into…

Answer 2

• epiblast which gives rise to the embryo proper (dorsal-back)
• hypoblast which gives rise to the primary (extraembryonic) endoderm that forms the yolk sac (ventral-belly)

Question 3

What is the primitive streak?

Answer 3

First marker of the craniocaudal axis. It occurs on the dorsal side of the epiblast and near the caudal end of the epiblast. The cranial end of the streak proliferates the become the primitive node and results from proliferation and migration of cells

Question 4

How do we turn the 2 layer disc into a 3 layer disc

Answer 4

Through gastrulation. There is a depression in the primitive streak called the primitive groove and it is the site along which the cels migrate through the epiblast. The first cells to migrate (ingress) through the epiblast form the endoder (and displace hypoblast cells). Later cells form the mesoderm, and non-ingressing cells form the ectoderm. Two populations of cells that migrate through the streak generate the 3 layer disc from the 2 layer disc

Question 5

What is gastrulation

Answer 5

Process by which the three germ layers are formed through cell migration

Question 6

What are the 3 ways in which cells can migrate through the epiblast and why is that important

Answer 6

1. Through the node
2. Near the node
3. Away from the node

It is important because they create three different cell fates. Where you migrate through the primitive streak helps to determine your fate

Question 7

How is the neural tube formed

Answer 7

Dorsal ectoderm becomes the neural plate. Lateral edges become elevated to form neural folds and mid region becomes depressed and form the neural groove. Neural fold moves toward each other and fuse to become the neural tube. Neural tube then detaches from the overlying ectoderm

Question 8

What does the nonneural ectoderm become

Answer 8

The skin

Question 9

What does the neural ectoderm become

Answer 9

The brain and spinal cord (CNS)

Question 10

What germ layer does the notochord derive from

Answer 10

Mesoderm

Question 11

What is neurlation

Answer 11

Formation of the neural tube

Question 12

How do cells fuse during neurulation

Answer 12

Cells in the middle of the neural folds fuse first and zippers both anteriorly and posteriorly at the same time

Question 13

What are cranial and caudal neuropores

Answer 13

Transient openings at either end of the neural tube after zippering of the neural folds occur

Question 14

How dour the defects or neural tube defects occur? How should women avoid neural tube defects?

Answer 14

• when the nuropores do not close correctly

- consume more folic acid

Question 15

What are the functions of the notochord

Answer 15

• transient structure that defines the body axis
• provides rigidity to the embryo
• functions as a signaling center to, at least, induce neural fates such as which neural cells become dorsal or ventral
• precursor for the axial skeleton

Question 16

Which germ layer forms the neural crest

Answer 16

Ectoderm

Question 17

What are the neural crest cells

Answer 17

Migratory cells that are ectoderm-derived and migrate throughout the body to give rise to a diverse number of cell fates

Question 18

What are the 4 regions of the mesoderm

Answer 18

1. axial (chordamesoderm)
2. Parasail mesoderm
3. Intermediate mesoderm
4. Lateral plate mesoderm

Question 19

Axial (chordamesoderm)

Answer 19

Gives rise to the notochord

Question 20

Paraxial mesoderm

Answer 20

Gives rise to somites, adjacent to the neural tube

Question 21

Intermediate mesoderm

Answer 21

Gives rise to the kidney/gonads

Question 22

Lateral plate mesoderm

Answer 22

Gives rise to the lining of the organ cavities

Question 23

What are the derivatives of the endoderm

Answer 23

Gives rise to the GI tract, epithelial lining of lung buds and trachea, liver, gall bladder, and pancreas