Embryology

Question 1

What is Embryology

Answer 1

the branch of biology that deals with the formation, early growth and development of living organisms

Question 2

in what order does the embryologic timeline of events occur?
- formation of 3 fundamental cell types
- post embryonic development
- fertilisation
- emergence of body plan
- early cell division

Answer 2

1. fertilisation
2. early cell division
3. formation of 3 fundamental cell types
4. emergence of body plan
5. post-embryonic development

Question 3

what is a zygote?

Answer 3

a single celled organism resulting from the fusion of male and female pro-nuclei

Question 4

What are the components of the early stage blastocyst

Answer 4

• inner cells mass (embryo/foetus proper)
• trophoblast (placental and foetal membranes) outer layer

Question 5

what are the components of the late stage blastocyst

late stage blastocyst

Answer 5

Question 6

What are the 3 germ layers of the late blastocyst

tissues derived from each primary germ layer

Answer 6

• ectoderm (skin epidermous, nervous system)
• mesoderm (muscle, bone, blood, vessels, kidney, gonads, skin dermis, connective tissue)
• endoderm (gut, liver, lungs, pancreas)

Question 7

What is gastrulation

Answer 7

• a process of cellular rearrangement which involves migration, invagination and differentiation to form a tri-laminar disc
• the process that forms the 3 germ layers]
• occurs between implantation and organogenesis
• the basic body plan and primary body axis are established

Question 8

what is the first visual sign of gastrulation

Answer 8

formation of the primitive streak and primitive node

Question 9

what is the primitive streak

Answer 9

a midline groove in the embryo where epiblast cells migrate from the caudal end to the cranial end

Question 10

what is the primitive node

Answer 10

the end of the primitive streak where cells build up and release transcription/growth factors

Question 11

How is the Endoderm formed

Answer 11

formed by epiblast cells that migrate through the prmitive pit and displace the hypoblast cells

Question 12

how is the mesoderm formed

Answer 12

by epiblast cells that migrate through the primitive pit and lie between the epiblast layer and the newly created endoderm

Question 13

how is the ectoderm formed

Answer 13

by epiblast cells that remain in position

Question 14

what is the end point of gastrulation

Answer 14

the bilaminar disk is transformed into a tri-laminar disk

Question 15

what cells become the notochordal process

Answer 15

pre-notochordal cells migrating through the primitive node

Question 16

what does the notochordal process form

Answer 16

the notochordal plate (this allows pressure equilibrium

Question 17

how is the notochord formed

Answer 17

the notochordal plate fuses together (gives structure for the embryo to develop)

Question 18

What formed the neural tube

Answer 18

the neural folds fusing (neurulation)
- this occurs both cranially (to form brain) and caudally (to for spinal chord)

Question 19

what system is derived from the formation of the neural tube

Answer 19

the Central nervous system

Question 20

what structures are derived from the neural crest

Answer 20

structures that work closely with the CNS

Question 21

how is the neural crest formed

Answer 21

when some ectodermal cells from the neural tube migrate

Question 22

what beings neurulation

Answer 22

the notochord

Question 23

in summary, what is the ptocess of gastrulation

Answer 23

the change from bi-laminar disk to tri-laminar disk

Question 24

what are the key stages of neurulation

5

Answer 24

1. notochord formation
2. neural ectoderm/neural plate
3. neural folds
4. neural tube
5. neural crest

Question 25

label

Answer 25