Development of PNS Flashcards
What divides the neural tube into dorsal and ventral regions
Sulcus limitans
What type of cells do not come from the neuroepithelium
Mesenchymal cells which form microglial cells
Neuroepithelium forms what 3 main types
Apolar neuroblast - goes to bipolar, unipolar, and then to typical nerve
Glioblast - goes to astroblast then proplasmic astrocyte and fibrous asctrocyte OR glioblast goes to oligodendroblast and then oligodendrocyte
Ependyma - the cells that makes CSF which are preferred
What are the different layers of the neural tubes from closest to lumen to most distant
Ventricular zone - stem cells undergoing mitosis
Mantle/intermediate zone - migrating cells that undergo differentiation into neurons or glia and they extend their neurons farther away
Marginal zone - mostly axons that will eventually be myelinated
What plate forms what will be the dorsal side of the cord
Alar column and roof plate
What plate forms the ventral side of the cord
Basal column and floor plate
What causes motor and sensory neurons to form
Increased SHH is motor; decreased is sensory
What does SHH activate downstream
NKX2.2 and NKX6.1
What counteracts SHH gradient
BMP and TGFb
What does BMP4 activate
PAX3 and 7
What forms first in the spinal cord, motor neurons or sensory neurons
Motor
Sympathetic ANS intermediolateral columns are where
T1-L3
What plate undergoes differentiation to become interomediolateral columns
Dorsal most basal plate
What do intermediolateral columns eventually form
Lateral horns
Intermediolateral columns in s2-s4 make up what
The parasympathetic division of ANS
Ectodermal placodes give rise to
The senses
In the trunk, NCC give rise to
Sensory neurons in DRG, schwann cells, sympathetic ganglion, enteric nervous system (digestion)
Axons exiting through the ventral horn pass through the cranial sclerotome and form
The ventral root
What are the components of the spinal nerve
Dorsal root, ventral root, and visceral MN from lateral horn
How many neurons are typically in an autonomic activation? Somatic
2, 1
Which has a wider net of neurons activating it, sympathetic or parasympathetic
Sympathetic, there are 2 neurons involved
What do preganglionic neurons come from
Neuroectoderm
When do the preganglionic neurons form
Week 5
What myelinates CNS and when? PNS?
Oligodendrocytes, 6 months to puberty, older tracts first
Schwann cells
Motor before sensory, 4th month
