Neurological Development Two Flashcards
What does gastrulation result in?
The formation of three primary germ layers
What are the three primary germ layers?
Endoderm
Mesoderm
Ectoderm
What is the definition of gastrulation?
The formation of three primary germ layers and the notochord is developed in this time.
What two features of a cell are inversely proportional
The plasticity/capacity for self renewel of a cell diminishes as its function increases.
What sort of cells important in growth are highly plastic but not very functional?
Stem cells
What does the endoderm give rise to?
Linings of the internal organs, gastrointestinal, respiratory, endocrine
What does the mesoderm give rise to?
Muscles and connective tissue
What does the ectoderm give rise to?
Brain and skin.
Following sex what must occur before a blastocyte can form?
Two germ cells (egg and sperm) must fuse and this results in stem cells, leading to blastocyte and trophoblast formation etc…
Whats the first essential step following early blastocyte formation that allows brain formation?
Gastrulation - as ectoderm has formed
What are the next four steps following gastrulation?
Induction
Neuralisation
Fusion (end of neuralisation)
Vesicle formation
What is induction?
Induction is the development of different tissues and layers because of the influence from other tissues.
pretty much : How different tissue types form
What mediates induction?
Growth factors mediate the induction process
What are the main growth factors in Brain development?
BMP4 (Bone Morphogenetic Protein 4
What is BMP4’s antagonists?
Noggin or Chordin
Why does BMP4 have antagonists?
Different concentrations of growth factors (hence antagonists) produce different affects / growth levels on cells)
What secretes BMP4?
Notochord
What does BMP4 without antagonist do?
Induces ectoderm to become epidermis
How does BMP4 induce CNS development?
BMP4 when inhibited slightly by chordin or noggin causes anterior neuroectoderm to form (brain)
What induce the spinal cord to form?
BMP4 and fibroblast growth like factor causes posterior neuroectorderm to form
At what stage of development does BMP4 take effect?
INduction, during the formation of neural plate
What is the process of neuralation?
The formation of the nerual tube
What is also an essential factor that influecnes the outcome of induction effects of BMP4?
The time it occurs during the developing fetus
What causes the neural tube to form?
The notochords secretion of growth factor?
Why does a neural tube form?
THe notochord causes different parts of the neural plate to grow at different rates
IN which direction does the neural tube close?
(Rostral) Tail - Head (Caput)
While the neural tube is forming, what else is happening in the same region?
A cluster of cells between the brain and skin form - called nueral crest
What does nerual crest give rise to?
PNS Many structures esp of face - Neurons and glia of face - Nuerons and glia of PNS of face - Sensory neurons of face and their glia - Sympathetic adrenal cells - CT - Bone and cartilage
What are two possible outcomes of neural tube failure to close?
Anterior neural tube pore = anencephaly
Posterior neural tube pore = spina bifida
What would result from a anterior neural tube pore?
Anencephaly = no brain development
Most fetuses undergo spontaneous abortion as do not meet checkpoint standards
What would result from posterior neural tube pore?
Spina bifida - Can be detected
What are the forms of spina bifida?
Spina bifida Occluta = hidden malclosures in the spinal column asmptomatic and do not pose pathological threat
Spina bifida cystica = external fluid filled sac, contains protruding neurons and CSF
Whats significant at four weeks of development?
3 vesicles have formed
Prosencephalon (forebrain)
Mesenscephalon (midbrain)
Rhombancephalon (hindbrain)
Between 4-6 weeks what is significant with regards to the vesicles?
Five vesicles have formed
The prosencephalon has given rise to:
Two telencephalon (L and R cerebral hemispheres)
Diancephalon (Thalamus and some hypothalamus)
The mesencephalon still exists as is
The rhombancephalon has given rise to:
Metancephalon which froms the cerebullum
Myeloncephalon which forms the pons and gthe medulla
Why does the brain fold during development?
AS different parts grow at different rates (known as flexures)
What are some important folds during development?
Midbrain Flexure
Cephalic flexure
Pontine flexure
Cervical Flexure
During induction what does the ectoderm closest to the notochord become?
Neuroectoderm
Induction gives rise to the?
Neural plate
What is the difference between caudal and rostral?
Rostral is towards the front of the brain, while caudal is the back towards the spinal cord i.e posterior and inferiorly.
With Neural tube closure, which ends failing to close results in what?
Rostral and caudal malclosure results in anencephaly. As both terms refer to the cerebral cortex.
