Introduction to Embryology

Question 1

When does implantation occur after fertilisation?

Answer 1

7-8 days

Question 2

What does the blastocyst divide into?

Answer 2

1) Embryoblast (Inner cell mass)

2) Trophoblast (Outer cell mass)

Question 3

What does embryoblast divide into?

Answer 3

Epi and hypoblast (BLD)

Question 4

What does trophoblast divide into? 2)

Answer 4

1) Cytotrophoblast (Inner)

2) Syncytiotrophoblast (outer)

Question 5

What happens in 3rd week of pregnancy?

Answer 5

Trilaminar disc forms (Gastrulation as mesoderm forms)

Question 6

What happens in fourth week?

Answer 6

Folding of the TLD into cylindrical embryo

Question 7

What is formed from ectoderm?

Answer 7

Skin, hair, nails, CNS, PNS, PPG and sweat glands

Question 8

What is formed from endoderm?

Answer 8

Respiratory tract, GI tract, urinary and auditory tube, liver, pancreas, thyroid and parathyroid glands. (Lots of internal organs)

Question 9

Which part of TLD form somites?

Answer 9

Paraxial plate mesoderm

Question 10

Which part of TLD forms circulatory system?

Answer 10

Lateral plate mesoderm

Question 11

What do epiblasts develop into?

Answer 11

Ectoderm

Question 12

What do the mesoderm form?

Answer 12

Connective tissue in between Musc, bones and cart. Also urogenital system and blood vessels

Question 13

What forms and is the function of Notochord? (2)

Answer 13

1) Bottom of embryo from mesoderm folds to form it

2) Notochord releases chemical messengers to affect overlying ectoderm, causing infolding in neural tube CNS