Basics of Brain Development Flashcards
What is the embryo called at day 4, before blastulation?
Morula
What is the embryo become during blastulation and when does this occur?
▪️ Blastula followed by a blastocyst
▪️ From ~day 5-6 to day 21 (3 weeks)
What is the blastocysts made up of?
▪️ Trophoblast - outer layer
▪️ Inner cell mass
▪️ Blastocoel
What does the inner cell mass of the blastocyst become?
▪️ Hypoblast
▪️ Epiblast
Which part of the inner cell mass differentiates into the ectoderm, mesoderm, and endoderm?
The epiblast
When does gastrulation occur?
3 weeks post conception (E13)
What happens during gastrulation?
▪️ The blastocyst becomes a multidimensional layered structures
▪️ Formation of the ectoderm, mesoderm, and endoderm
▪️ Ectoderm differentiates into skin and the neural plate
What happens if gastrulation goes wrong?
Conjoined twins
Where do the microglia come from and when do they arrive in the brain?
The mesoderm
Arrive in the brain via circulation around day 28
What happens to cell division around day 25?
▪️ Symmetrical
▪️ Producing neural progenitor cells
Which cells of the ectoderm differentiate into skin and why?
▪️ Ventral cells
▪️ BMP-4 binds to them
Which cells of the ectoderm form the neural plate and why?
▪️ Dorsal cells
▪️ The organiser on the ventral side releases chordin and noggin which prevent BMP-4 from binding
What are the main roles of microglia during neurodevelopment?
▪️ Phagocytosis
▪️ Formation and guidance of axons to white matter
▪️ Organisation of the nervous system
▪️ Neurogenesis, synaptogenesis, and synaptic pruning
When does gastrulation end?
Day 28
What condition occurs during gastrulation if an individual has one copy of the CSF1R gene mutation?
Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP)
▪️ WM abnormalities
▪️ Myelin loss
▪️ Cognitive and motor problems
What happens during gastrulation if someone has two copies of the CSF1R gene mutation?
▪️ No microglia
▪️ Corpus callosum agenesis
▪️ Disorganised brain
(poor prognosis)
When does neurulation start?
Day 22
What happens to the neural plate during neurulation?
It folds together, from the middle outwards, forming the neural tube
When does the rostral part of the neural tube close and what happens if this is incomplete?
▪️ At the beginning of week 4
▪️ Incomplete closure = ancephaly