EMBRYOLOGY

Question 1

What is embryology

Answer 1

Is the process by which a multicellular organism arises from a single cell

Question 2

List the types of basic cell movement

Answer 2

Invagination 
Involution 
Ingression
Delamination 
Epibody 
Convergence 
Extension 
Cavitation

Question 3

What is invagination

Answer 3

Including of a layer of cells

Question 4

What is involution

Answer 4

Outer cellular layer growing on the inside of the layer

Question 5

What is ingression

Answer 5

Invasion of cells into an embryo

Question 6

What is delamination

Answer 6

One layer splitting into two layers

Question 7

What is epibody

Answer 7

Second layer on outer surface

Question 8

What is convergence

Answer 8

Cells converge towards central midline point

Question 9

What is extension

Answer 9

Cells group together and form long cylindrical like structure

Question 10

What is Cavitation

Answer 10

Where spaces are formed

Question 11

What is an oocyte

Answer 11

Egg cell

Question 12

What is a zygote

Answer 12

Egg and sperm nuclei have fused

Question 13

What is a morula

Answer 13

Contains lots of early cells - can’t count how many

Question 14

What is gastrulation

Answer 14

Process where the 3 primary germ layers (endoderm, mesoderm and ectoderm) are established in the embryo
The basic body plan is established
The primary body axes are established

Question 15

What is the primitive streak

Answer 15

A depression in the surface of the epiblast

Question 16

In what direction does the primitive steak form

Answer 16

Grows crainally

Question 17

What starts the formation of amniotic fluid

Answer 17

Embryo implantation- causes cell death in epiblast

Question 18

Describe the process of gastrulation

Answer 18

Some epiblast cells detach and move towards primitive steak and node. They slip beneath the epiblast , then some of the cells then displace the hypoblast

Question 19

In gastrulation which cells form the endoderm

Answer 19

The cells that displace the hypoblast become the endoderm

Question 20

In gastrulation which layer of cells become the mesoderm

Answer 20

The cells that lie between the epiblast and hypoblast become the mesoderm

Question 21

In gastrulation which cells become the ectoderm

Answer 21

The cells remaining in the epiblast

Question 22

What is neurulation

Answer 22

Formation of neural tube

Question 23

What is the notochord

Answer 23

Extended columns of cells ventral to the central nervous system. Induces the formation of the neural tube

Question 24

How is the notochord formed

Answer 24

1. Cells that form mesoderm move in a cranial direction
2. Cells in hypoblast intercalate to form notochordal plate
3. Hypoblast cells replaced by endoderm. Cells of the plate proliferate and detach to become notochord
4. Notochord produces growth factors which act on the ectoderm, starting the formation of the neural tube

Question 25

In what direction does the notochord develop

Answer 25

Head to tail direction

Question 26

What is the effect of the notochord on the ectoderm above

Answer 26

The growth factors produced by the notochord causes ectoderm to thicken and form neural plate

Question 27

How does the neural tube develop

Answer 27

1. Notochord induces formation of neural plate
2. Lateral edges of neural plate elevate to form folds (and depressed mid region becomes neural groove )
3. Folds fuse together- occurs in cervical region and precedes in both directions - forming neural tube

Question 28

What are neural crest cells also known as

Answer 28

4th germ cell layer

Question 29

How are neural crest cells formed

Answer 29

Get cut off after closure of the nurrral tube

Question 30

What do neural crest cells form

Answer 30

Many rural and skeletal and other cell types

E.g form sympathetic and parasympathetic components of the PNS