Development of PNS Flashcards
4th somite and above (superiorly)
brain
below 4th somite (5th…) (inferiorly)
spinal cord
Gray Matter
location of the cell bodies of the neurons that make the H shape in the spinal cord; they are not myelinated
Dorsal or posterior horn
sensory (afferent neurons)
Lateral horns
autonomics; only T1-L2
Anterior or ventral horns
motor (efferent nuerons)
White Matter
Mainly myelinated axons surrounding the H
Dorsal or posterior funiculus
sensory axons
Lateral funiculus
sensory and motor axons
Ventral or anterior funiculus
primarily motor axons
Alar Plate
Sensory neurons that stay completely in CNS
Basal Plate
motor neurons in skeletal muscle and pre-synaptic neurons for autonomics
Sulcus limitans
separates the Alar and Basal plate
Ventricular zone
right next to neural canal; stem cells can give rise to other cells to migrate up to intermediate zoneor stay and give rise to epindymoblast and then ependymal cells which will line ventricles and central canal
choroid plexus cell
makes CSF; comes from epindymoblast
Intermediate zone
stem cells that migrate in and form neurons, astrocytes (structural), and other cells; gray matter
Marginal zone
Axons that are myelinated; oligodendrocytes in CNS and Schwann cells in PNS
Arising from neural tube (neuroectoderm)
dendrites, astrocytes, oligodendrocyte, and the choroid plexus
Microglial cells
arise from mesoderm; monocytes of brain and spinal cord (macrophages)
Position of spinal cord in newborns
L2 or L3; must go lower for puncture
position of spinal cord in adults
L1 or L2
Give rise to spinal ganglion cells and sensory neurons in periphery
neural crest cells
How to make alar plate
high BMP from roof plate and surface ectoderm activate PAX3 and PAX7; DORSAL
how to make basal plate
High Shh from notochord and floor plate activated NKX2.2k and NKX6.1; VENTRALLY
how to make ventral motor neurons
slightly less Shh and slightly more BMP activates NKX6.1 and PAX6
GSE
General somatic efferent; motor neurons for muscle from somites; from NEUROECTODERM
GVE
General visceral efferent; autonomic motor neurons to smooth and cardiac muscle; from NEUROECTODERM
SVE
Special (brachial) visceral efferent; motor neurons for muscles derived from pharyngeal arches; from NEUROECTODERM
GSA
General somatic afferent; sensory neurons in skin, joint capsules, tendons, muscles; from ectoderm or adjacent to ectoderm; NEURAL CREST DERIVED
GVA
General visceral afferent; sensory neurons from endoderm or mesoderm derived adjacent to endoderm; organs; NEURAL CREST DERIVED
SSA
Special somatic afferent; hearing, balancing, and sight
SVA
Special visceral afferent; taste and smell
short, myelinated fibers derived from neuroectoderm
Pre-ganglionic cells from spinal cord of sympathetic NS
longer, not myelinated fibers derived from neural crest
post-ganglionic cells from spinal cord of sympathetic NS
long myelinated from neuroectoderm
pre-ganglionic of parasympathetic
short not myelinated from neural crest
post-ganglionic of parasympathetic; found in walls of the organ
sources of PNS
neural crest and ectodermal placodes
cranial nerves that parasympathetic travel on
3,7,9, and 10
sacral nerves for parasympathetic
S2, 3, and 4
when does the CNS become myelinated
6th month through puberty; from neuroectoderm
PNS myelination timeline
4th month in utero when baby kicks; motor before sensory; SCHWANN cells; from neural crest
