Brain Development in Paediatrics Flashcards
When does human brain development commence?
3rd week post conception
Which intrauterine factors may negatively impact the development of the nervous system?
- Maternal health and disease
- Insults (physical or infection)
- Placental or nutritional issues
Which extrauterine factors may negatively impact the development of the nervous system?
- Nutrition or environmental toxins
- Emotional and social factors
- Exposure to alcohol or drugs
How long does the embryonic period last?
Conception until gestational week 8
How many layers is the embryo comprised of during the embryonic period and what are they called?
2
Epiblast and hypoblast
The primitive streak is a transient structure that marks what?
The start of gastrulation
What happens in gastrulation?
The formation of the trilaminar embryonic disc, which is comprised of the three germ layers (ectoderm, mesoderm and endoderm)
What is the role of the primitive node?
Determines migration of cells into cleft where cells form 3 layers
Which adult tissues form from the ectoderm?
- Skin
- Nails
- Hair
- Neural tissue
Which adult tissues form from the mesoderm?
- Muscle
- Bone
- Cartilage
- Vascular system
Which adult tissues form from the endoderm?
- Gut
- Respiratory
Between which days of development is the neural tube expected to develop?
20-27
Which cells is the neural crest derived?
Neural progenitor cells
(from neural plate)
Failure of the neural groove, and then tube, to close results in what?
Neural tube defects
Which cells line the inside of the neural tube and what is this zone called?
Neural progenitor cells
Ventricular zone
The hollow centre of the neural tube will develop into what?
- Ventricular system
- Central channel of spinal cord
Which aspect of the neural tube will become the brain?
Anterior/rostral tube
Which aspect of the neural tube becomes the spinal cord?
Caudal tube
What are the three primary brain vesicles in a three to four week embryo?
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
How many secondary brain vesicles develop in a five week embryo?
5
Which two signalling molecules influece the development of the neocortex?
- EMX2
- PAX6
A high PAX6 concentration and low EMX2 concentration induce progenitor cells to develop into what?
Motor neurones
A high EMX2 concentration and low PAX6 concentration induce progenitor cells to develop into what?
Visual cortical neurones
What is required in the foetal period in order to accomodate the proliferating neural cell populations?
Development of gyri and sulci
How are neurones produced during the foetal period?
Neuronal progenitor cells (in ventricular zone) divide initially symmetrically to produce two neural progenitor cells
Asymmetrical division follows producing one progenitor cell and one neurone
When neurones are produced, where do they migrate?
Developing neocortex
In terms of brain development what are two of the main processes which occur postnatally?
- Continued proliferation and migration
- Myelination
In which sequential manner does myelination occur in the brain postnatally?
- Bottom to top
- Front to back
For how long does myelination occur postnatally?
- Mainly in first 2 years
- Continues into 20s
Physical maturation of the brain in adolescent years is associated with what?
Rising gonadal hormone concentrations
What is holoprosencephaly?
A cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to develop into two hemispheres
In terms of myelin, what is the PLP1 gene responsible for?
Encodes the most predominant transmembrane proteolipid protein in myelin
Responsible for compactation, stabilisation and maintenance of myelin sheaths, development of oligodendrocytes and axonal survival
Where is the PLP1 gene located?
X chromosome
What is the most severe condition associated with a PLP-1 mutation?
Pelizaeus-Merzbacher disease
When does Pelizaeus-Merzbacher disease present and how?
Infancy or early childhood
- Nystagmus
- Hypotonia
- Cognitive impairment
- Progresses to severe spasticity and ataxia
- Short life span
