Neurobiology Exam 2

Front 1

Neural crest cells

Back 1

-cells in neural crest at most dorsal part of the tube migrate into periphery of the body
-cells migrating dorsally become melanocytes
-cells migrating ventrally become part of the PNS (DEG, sympathetic, glial cells, adrenal medulla)

Front 2

Lateral epidermis

Back 2

-important in causing proper folding of neural tube
-hinge region induces right-side-out folding

Front 3

Pax3

Back 3

-a gene expressed in entire neural plate
-two Pax3 gene mutations prevenst neural tube from folding
-one Pax3 gene mutation causes Waardenburg Syndrome: incomplete pigmentation (albino hair or skin at ventral midline)

Front 4

Neural tube

Back 4

-closes inward in several places in humans
-most caudal regions close last
-closes between 22-28 days of gestation inhumans
-failure to close causes anencephaly (rostral end), spina bifida (caudal end), or encephalocele (middle)

Front 5

Stages of neural tube development

Back 5

-three vesicle stage early on incluseds proencephalon, mesencephalon, rhombencephalon (listed rostral to caudal)
-five vesicle stage adds vesicle in forebrain (gives rise to 1a and 1b) and a vesicle in hindbrain (gives rise to 3a and 3b)
-neural tube bends at the cephalic, pontine, and cervical flexures

Front 6

Regions of neural plate

Back 6

-basal region = ventral region after closure
-alar region = dorsal region after closure
-dorsal regions concerned with sensory info
-ventral regions concerned with motor functions

Front 7

Non-neural tissue

Back 7

-floor plate (ventral)
-roof plate (dorsal)

Front 8

Notochord

Back 8

-induces floor plate at ventral base of neural tube
-induces ventral spinal cord structures

Front 9

Floor plate

Back 9

-located at ventral base of neural tube
-regulates and induces ventral cell types (works with notochord)
-induces motor neurons

Front 10

Roof plate

Back 10

-located at dorsal side of neural tube
-regulates and induces dorsal cell types (works with epidermis)
-

Front 11

Sonic Hedgehod (Shh)

Back 11

-protein secreted from notochord
-induces formation of floor plate and Shh expression in floor plate
-activity is determined by graded concentration
-high concentration ventrally, low in intermediate portion, absent dorsally
-Required for formation of ventral structures

Front 12

Phases of Shh cascade

Back 12

1) regulate other transcription factors
2) transcription factors mutually repress each other
3) neuron-generating region is divided into progenitor zones

Front 13

Phase 1 of Shh cascade

Back 13

-regulate other transcription factors
-depends on Shh concentration
-cass II TF are at most concentrated end (most ventral)

Front 14

Phase 2 of Shh cascade

Back 14

-transcription factors mutually repress each other
-class I and class II TF repress each other
-defines borders of expression

Front 15

Phase 3 of Shh cascade

Back 15

-neuron-generating region is divided into progenitor zones
-progenitor cells within areas of TF generate neural types depending on what TF they express
-These TF cause expression of specific other factors as progeny are made

Front 16

BMP

Back 16

-gradient similar to Shh but in dorsal tube

Front 17

dll-3 neurons

Back 17

-initially cell body is positioned dorsally, migrates slightly ventrally
-commissural neurons
-project axons across ventral midline

Front 18

dl4-6 neurons

Back 18

-move dorsally in spinal cord
-association neurons
-receive nociceptive info
-project to commissural neurons, which coordinates response from two sides of CNS

Front 19

Renshaw cells

Back 19

-provide collateral inhibition during stretch
-down-regulate excitability in motor neuron to modulate contraction

Front 20

Ia neurons

Back 20

-inhibitory interneurons reduce activation of opposing muscle so stimulated muscle can contract

Front 21

Classes of motor neurons in thoracic area

Back 21

-medial subdivision innervates axial muscle near spinal cord and allows back movement
-lateral subdivision innervates thoracic body
-CTv project to sympathtic ganglia and innervate postganglionic neurons

Front 22

Classes of motor neurons in hindlimb area

Back 22

-lateral subdivision innervates dorsal limb muscles
-medial subdivision innervates ventral limb muscles