Embryology Revision

Question 0

True or false:

all cells of the blastocyst are totipotent

Answer 0

False
1st differentiation has occurred in blastocyst
Only cells in inner cell mass become embryo; outer cell mass becomes placenta

Question 1

True or false:

the morula implants in the uterine stroma

Answer 1

False

Implants when is a blastocyst

Question 2

True or false:

each of the three germ layers arises from the epiblast

Answer 2

True
Epiblast detaches from neighbouring cells & migrates thru primitive streak, forming 3 germ layers
Hypoblast displaced by endoderm (from epiblast) in gastrulation & disappears

Question 3

True or false:
in the trilaminar embryo, ectoderm and endoderm are NEVER
in contact, there is always mesoderm between them

Answer 3

False

Buccopharyngeal & cloacal membranes do not have mesoderm

Question 4

True or false:
the notochord has an important role in development of
the nervous system

Answer 4

True
Notochord (specialised mesoderm) formed from gastrulation, signals overlying ectoderm to form neuroectoderm of neural plate, which goes on to form neural tube & then nervous sys

Question 5

True or false:

Hypoblast is called endoderm after gastrulation

Answer 5

False

Hypoblast disappears

Question 6

True or false:

Mesoderm lines the intraembryonic coelom

Answer 6

True

Question 7

Which of the following are true: 
The notochord: 
(a) drives neurulation 
(b) is formed during gastrulation 
(c) is a hollow cord in the midline 
(d) has no function in adult life 
(e) forms the nucleus pulposus of intervertebral disk 
(f) is part of the spinal cord

Answer 7

a, b, d, e

Question 8

What is the fate of the chorionic cavity?

Answer 8

Disappears: embryo within amniotic sac grows into it

Question 9

Describe how the intraembryonic coelom is formed

Answer 9

Slit forms in lateral plate mesoderm, creating somatic & splanchnic mesoderm

Question 10

Suggest an adult derivative of the splanchnic layer of lateral plate mesoderm

Answer 10

Smooth muscle of GIT

Question 11

What are neural crest cells?

Answer 11

As neural tube forms, population at lateral edge forming tube detach from other cells of neuroectoderm tube & migrate widely throughout the body

Question 12

which of the following receive a contribution from the neural crest in development:
A) Nervous system 
B) Heart 
C) Face 
D) Limbs

Answer 12

a, b, c

Question 13

On which surface is the onset of gastrulation visible, and what is visible

Answer 13

Epiblast

Primitive streak/node/pit

Question 14

Why does the buccopharyngeal & cloacal membranes have no mesoderm?

Answer 14

No mesoderm = no CVS = avascular = tissue does/regresses

Question 15

Saccrococcygeal teratomas are large abnormal growths in the saccrococcygeal region and are the most common tumours in newborns.
Given that the developmental basis for these tumours is persistence of the primitive streak beyond the time when it should normally
regress, suggest why these tumours can be composed of many discrete tissues types (such as cartilage, glandular elements etc).

Answer 15

Cells of primitive streak still pluripotent; capacity to differentiate into many types of tissues