3. Development of the Nervous System Flashcards
Nervous System is DERIVED from which germ layer
ECTODERM
the BLASTOCYST gives rise to the BILAMINAR DISC (EPIBLAST & HYPOBLAST) with the formation of fluid-filled AMNION and PRIMARY YOLK SAC by DAY…
DAY 8
on which DAY does the PRIMITIVE STREAK become MESODERM, ENDODERM, ECTODERM (tri-laminar disc)
(embryo trilaminar except at the area of the primitive mouth and at the cloaca)
DAY 15
how is the NOTOCHORDAL PROCESS formed
ROSTRAL (front) part of PRIMITIVE STREAK INVAGINATES to give the PRIMITIVE PIT which EXTENDS ROSTRALLY (anteriorly) with the cells that form the pit
- becoming Notochordal Process
NOTOCHORDAL PROCESS undergoes FUSION with the ENDODERM but then REFORMS as the…
NOTOCHORD - which is MESODERMAL
from DAY 18 what does the NOTOCHORD (mesoderm) do
releases CHEMICALS that cause INDUCTION of the overlying ECTODERM to INFOLD
- to form the NEURAL PLATE
-> neural groove -> neural folds – (fuse) -> neural tube
NEURAL PLATE is INDUCED in the ectoderm by the ..
NOTOCHORD (just below)
which CELLS of the NERVOUS SYSTEM are (not) DERIVED from the NEURAL TUBE
ALL NEURONES
all GLIA (EXCEPT MICROGLIA)
CELLS that DETACH from the NEURAL TUBE (‘pinched off’) are the
NEURAL CREST
NEURAL CREST CELLS give rise to..
PERIPHERAL NERVOUS SYSTEM and SCHWANN CELLS
& MENINGES, other specialised cells ie cells of ADRENAL MEDULLA and cutaneous MELANOCYTES in skin
OPEN ENDS of the NEURAL TUBE are the …
when do they CLOSE
ROSTRAL and CAUDAL NEUROPORES
ROSTRAL/ CRANIAL (anterior) : DAY 25
CAUDAL (posterior): DAY 28
BRAIN comes from dramatic Elaboration of the…
ROSTRAL (CRANIAL) part of the NEURAL TUBE
when do we have 3 PRIMARY BRAIN VESICLES
by END OF 4TH WEEK
when do we have 5 SECONDARY BRAIN VESICLES
5TH WEEK
what causes the Mouth to be anterior/ at the front and the brain to be at the top / superior in the body
FLEXURES of the embryo
3 PRIMARY BRAIN VESICLES are:
- PROSENCEPHALON
- MESENCEPHALON
- RHOMBENCEPHALON
5 SECONDARY BRAIN VESICLES are:
(week 5)
- TELENCEPHALON (cerebrum)
- DIENCEPHALON (thalamus, hypothalamus …)
- MESENCEPHALON (midbrain)
- METENCEPHALON (pons, cerebellum)
- MYELENCEPHALON (medulla)
BRAIN VESICLES are EXPANSIONS at the …. END of the NEURAL TUBE
ROSTRAL END (cranial)
PROSENCEPHALON divides into which SECONDARY BRAIN VESICLES
TELENCEPHALON (cerebrum) & DIENCEPHALON (-thalamus)
RHOMBENCEPHALON divides into which SECONDARY BRAIN VESICLES
METENCEPHALON (pons, cerebellum) & MYELENCEPHALON (medulla)
which BRAIN VESICLE forms the MIDBRAIN of the BRAIN STEM
MESENCEPHALON
which BRAIN VESICLE forms the CEREBELLUM
METENCEPHALON
which BRAIN VESICLE forms the CEREBRUM
TELENCEPHALON
which BRAIN VESICLE forms the MEDULLA of the BRAINSTEM
MYELENCEPHALON
which BRAIN VESICLE forms the THALAMUS & HYPOTHALAMUS etc
DIENCEPHALON
which BRAIN VESICLE forms the PONS of the BRAIN STEM
METENCEPHALON
how is the SPINAL CORD in relation to the SKELETAL SPINAL COLUMN
OUTGROWN by it as SPINAL CORD IS NOT AS LONG
SPINAL CORD ENDS AT L1
CAUDA EQUINA continues after it
what part of the SPINAL CORD is MOST SIMILAR to the early NEURAL TUBE
CENTRAL GREY MATTER (myelencephalon)
what part of the BRAIN is MOST SIMILAR to the early NEURAL TUBE
PERIAQUEDUCTAL GREY of MIDBRAIN (mesencephalon)
at what VERTEBRAL LEVEL does the SPINAL CORD END
L1
KEY STEP in CEREBRAL CORTEX DEVELOPMENT
NEURONAL MIGRATION
NEURONAL MIGRATION
where do they MIGRATE to and from
From VENTRICULAR ZONE
extend across ventricular surface (inner)
to the outer CORTEX / CORTICAL PLATE
what does NEURONAL MIGRATION do
INCREASES SURFACE AREA
what are KEY CELLS needed for the MIGRATION of NEURONS and for DEVELOPMENT of CEREBRAL CORTEX
RADIAL GLIAL CELLS
steps in neural development
- NEURULATION (formation of neural tube from neural plate)
- NEURONAL PROLIFERATION
- NEURAL MIGRATION
- MYELINATION (until early adulthood) (forming myelin on axons for faster signals)
also starting from migration:
SYNAPTOGENESIS
APOPTOSIS
what is SYNAPTOGENESIS
FORMATION of CONNECTIONS BETWEEN NEURONAL CELLS
which NEURONAL CELLS undergo APOPTOSIS
those that DON’T HAVE the right / SUCCESSFUL CONNECTIONS
which CHEMICAL / TROPHIC FACTOR allows neuronal cells with certain CONNECTIONS to SURVIVE / PERSIST and NOT UNDERGO APOPTOSIS
NGF - NERVE GROWTH FACTOR
results in ‘pruning’ of neural branches
which MORPHOGENS (Proteins) from the NOTOCHORD INDUCE the OVERLYING ECTODERM to become NEURAL CREST CELLS (neural PRECURSOR cells)
and NOT form EPIDERMIS (which would happen due to BMP4)
CHORDIN & NOGGIN
what PROTEIN from the NOTOCHORD INDUCES the VENTRAL/BASAL part of NEURAL TUBE to develop characteristics of MOTOR NEURONES and the DORSAL/ALAR Cells to develop characteristics of SENSORY NEURONES
SONIC HEDGEHOG (SHH)
role of NOTOCHORD
INDUCTION of ECTODERM above by release of proteins/chemicals
which part of NEURAL TUBE will become SENSORY due to SONIC HEDGEHOG INDUCTION
DORSAL / ALAR
(posterior)
which part of NEURAL TUBE will become MOTOR due to SONIC HEDGEHOG INDUCTION
VENTRAL / BASAL
what does NGF do
ALLOWS NEURAL CELLS with correct CONNECTIONS to SURVIVE
- NOT APOPTOSED
Trophic Factor
what do CHORDIN & NOGGIN do
INDUCE ECTODERM to FORM NEURAL CREST CELLS (which are neural PRECURSORS)
and NOT FORM EPIDERMIS
lack of NGF would mean
NO APOPTOSIS of FAULTY NEURAL CELLS in development
lack of CHORDIN & NOGGIN would mean
OVERLYING ECTODERM would become EPIDERMIS
(instead of CREST CELLS)
what causes DORSAL ROOT to be SENSORY and VENTRAL ROOT to be MOTOR in spinal nerves
SONIC HEDGEHOG (shh)
LATERAL VENTRICLES come from which BRAIN VESICLE
TELENCEPHALON
3RD VENTRICLE from which secondary brain VESICLE
DIELENCEPHALON
CEREBRAL AQUEDUCT from which brain VESICLE
MESENCEPHALON
UPPER PART of 4TH VENTRICLE from which brain VESICLE
METENCEPHALON
LOWER PART of 4TH VENTRICLE from which VESICLE
MYELENCEPHALON