Flashcards in (5) Cell diversity in developing nervous system Deck (89)
what is patterning?
organization of tissues into distinct cell types during development as a result of the unique activities of sets transcription factors and signaling proteins
what is a transcription factor
protein that binds to specific DNA sequences
turns gene on/off
DNA--> mRNA--> protein
the CNS is patterned along...
anterior-posterior (head to bottom)
dorsal-ventral (back to front)
lateral (sideways) axes
signalling factors are expressed either...
ventrally or dorsally
and turn on series of transcription factors that code the developing spinal cord in discrete molecular domains that presage the formation of distinct neural subtypes
signalling factors expressed ventrally are..
Sonic Hedgehog (Shh)
signalling factors expressed dorsally are...
Bone Morphogenetic Protein (BMP)
Wingless/Int related (WNT)
if the genes are misexpressed it can lead to...
cranial nerves are organized along.... & due to...
along anterior-posterior length of the head
due to interactions between the migrating neural crest cells with ectodermal thickenings called placodes
how are neural crest cells patterning?
by action of transcription factors called Hox genes
- they are expressed in nested domains along the anterior-posterior axis
what are Hox genes
differentiating neurons accumulate on the..... in region called...
outer layer of the spinal cord in region called marginal zone
marginal zone contains ...
post-mitotic (no longer dividing) neurons
the inside layer aka.... contains....
aka ventricular zone
contains dividing progenitors
what forms adjacent to the spinal cord
dorsal root ganglia
dorsal root ganglia are part of .... and contains...
part of peripheral nervous system
contains sensory input from periphery that connects to the developing spinal cord via dorsal root entry zone
all dividing cells line....
differentiating neurons move...
dividing cells line central canal of spinal cord
differentiating neurons move outward
3 major types of neurons in the spinal cord
LMC= lateral motor column, innervates limbs
MMC= medial motor column, innervates axial muscles
2 transcription factors involved in embryonic spinal cord
(interneurons an motor neurons)
what does Pax2 label
what does Isl1 label
motor neurons in ventral horn
- lights up DRG
what does the sulcus limitans do?
divides developing neural tube into posterior alar plate and anterior basal plate that will give rise to sensory and motor areas of the spinal cord and brainstem
location of alar and basal plate
Sonic Hedgehog in dorsoventral patterning of the spinal cord
- where is it released from
SHH released from mesoderm and later notochord
signals cells to form the basal plate
what does the notochord secrete?
SHH (Sonic Hedgehog)
in dorsoventral patterning of the spinal cord what does the ectoderm adjacent to neural plate release?
Bone morphogenetic proteins (BMPs) and Wingless/Int-related (Wnts)
signal cells to form the alar plate
what signals cells to form the basal and alar plate
alar= BMP, Wnt
signal molecules are secreted in graded manner in developing neural tube, the concentration is...
higher ventrally (Shh) or dorsally (BMP, Wnt)
why are the signalling molecules considered morphogenes
because they are able to pattern tissue in a concentration dependent fashion
3 transcription factors involved in dorsoventral patterning of the spinal cord
Pax6 (expressed by somites)
Olig2 (where future motor neurons come from)
FoxA2 (give rise to floor plate)