Embryology Introduction

Question 1

What happens on Day 7?

Answer 1

Blastocyst

Question 2

What happens in week 2?

Answer 2

Bilaminar disc

Question 3

What happens in week 3?

Answer 3

Gastrulation
Trilaminar disc (NS derived from ectoderm)
Neurulation

Question 4

Describe a blastocyst

Answer 4

Blastocyst contain inner cell mass (embryonic stem cells that will develop into all cells)

Question 5

How is the bilaminar disc formed?

Answer 5

Cells forming in the epiblast and hypoblast

Blastocyst to amniotic cavity and primary yolk sac with epiblast and hypoblast

Question 6

Describe gastrulation

Answer 6

Development of orientation between head and tail region
Primitive node induces primitive streak to form (tail region)
Epiblast ectoderm and endoderm

Question 7

How is the trilaminar disc formed?

Answer 7

Bilaminar disc evolves into trilaminar disc
Ectoderm mesoderm and endoderm
Nervous system derived from ectoderm

Question 8

Describe neurulation

Answer 8

Notochord
Chemical signalling from notochord results in changes in overlying ectoderm (neural plate) causing the neural groove to form

Question 9

How does neurulation continue into week 4?

Answer 9

Edges of the neural groove lifting to fuse with each other to form neural tube
Head to tail
Three primary brain vesicles:
Prosencephalon= forebrain
Mesencephalon= midbrain
Rhombencephalon= hindbrain

Question 10

What are the 5 secondary brain vesicles of week 5 and what do they turn into?

Answer 10

• The telencephalon becomes cerebrum, basal ganglia and lateral ventricles
• The diencephalon becomes thalamus, hypothalamus and 3rd ventricle and epithalamus, eye cup
• The mesencephalon becomes midbrain and cerebral aqueduct
• The metecephalon becomes the cerebellum and superior part of 4th ventricle and pons
• The myelencephalon becomes the medulla oblongata and inferior part of 4th ventricle

Question 11

Describe spinal cord development

Answer 11

Week 5= posteriorly sensory and anteriorly motor

Question 12

How does the brain grow?

Answer 12

Neuro precursor cells
Neurogenesis and gliogenesis
Development of cortex
Migrate outwards to cortex

Question 13

What is heterotopia?

Answer 13

Inadequate/ failure of migrating of nerve cells
Localised populations of neurones in centralised places that would be white matter
Greya matter to cortex
Epilepsy

Question 14

What other processes overlap with birth?

Answer 14

Apoptosis
Synaptogenesis
Myelination
Synaptic pruning
Maturation of innate and adaptive immunity