Neuroembryology Flashcards
Major milestones
Gastrulation
Neural Induction and Neurulation
Neurogenesis/Neuronal Proliferation
Cell Migration
Development of Axons and Dendrites
Synaptogenesis and Pruning
Myelination
Formation of Neural Circuitries
Nervous system develops between _ and _
4 weeks and adulthood
Brain weight at birth
800 g
Brain weight at 6 y/o
1200 g
Brain weight at adult
1400 g
_% of birth associated with major malformation of the CNS
3
_% spontaneous aborted fetus
75
_% of infants who die within the 1st yr of life have major CNS malformations
40
Conceptus wk
1-2
Embryonic development wk
3-8
Fetal period wk
9-38
Loss happens on
Conceptus
Major abnormalities happen on
Embryonic development
Functional and Minor abnormalities happen on
Fetal period
Early developmental process in which an embryo transforms from 1 dimensional layer of epithelial cells (blastula) and reorganizes into a multilayered and multidimensional (glastula)
Grastulation
Formation of trilaminar from bilaminar disc
Gastrulation
Gastrulation happens on wk
3
Gastrulation give rise to
Ectoderm
Mesoderm
Endoderm
Primitive node and streak
Process before gastrula
Zygote
Blastomere
Morula
Blastocyst
Blastula
Gastrula
Neural tissue appears at __wk
3rd
Embryo is composed of 3 primary germ layers
Ectoderm
Endoderm
Mesoderm
Ectoderm forms
CNS,skin
Mesoderm forms
Connective tissue, muscles, vascular structures, bone marrow, portions of internal organ
Endoderm forms
Lungs, liver, and gut
Establishes the basic body plan of all vertebrae
–midline axis, bilat sym, rostral and caudal ends, dorsal and ventral surfaces
Primitive streak
Defines the rostral direction
–as the node regresses, a notochordal process develops in the area rostral to it and somites begin to form on either side of the notochord
Primitive node/Hensen’s node
Induces epiblast cells to form neuroectoderm
Notochord
A process of cell to cell signaling by which the underlying mesoderm induces the ectoderm to become neuroectoderm and form the neural plate, giving rise to most of the nervous system
Induction
Neural induction takes place in the
ectoderm of the head process overlying the notochord
Neural induction starts about the
16th to 17th day of intrauterine life
Neuroectodermal induction is d/t
Hormones, growth factors, neurotransmitters
Notochord came from
axial mesoderm, day 16 - beginning of 4thweek
Directs the overlying ectoderm to form the neural plate
Induction (noggin & chordin)
Notochord defines the longitudinal axis by
production of cell adhesion molecules
Determine the orientation of the vertebral column
Notochord
Persist as the nucleus pulposus of the intervertebral disk
Notochord
Neural plate is formed on
Day 18
Neural fold is formed on
Day 20
Slipper-shaped plate of thickened ectoderm
Neural plate
Located in the mid dorsal region in front of the primitive gut
neural plate
Lateral edges become elevated to form the neural folds
Neural plate
Neural folds become more elevated, approach each midline and fuse to form the
neural tube
Neural folds form on Day
20
Day 21 neural folds touching each other forms the
neural tube
Primitive streak emerges as a groove at the
caudal (lower part) pole of the embryo
Primitive node emerges in the
cranial pole (upper part)
Epiblast cells moving along the primitive streak and the nodes form the
3 germ layers
Thickening of the ectoderm forms the
Neural plate in the cranial pole
Primitive streak in the caudal part initiates the
Gastrulation
Somites are made up of
Mesodermal cells