PSYC 2410 Chapter Notes - Chapter 9: Necrosis, Olfactory Bulb, Prefrontal Cortex
27 Jun 2018
School
Department
Course
Professor
Five phases of neurodevelopment
First, cells must differentiate; some must become muscle cells, some must become multipolar
neurons, some must become glial cells, and so on
Second, cells must make their way to appropriate sites and align themselves with the cells
around them to form particular structures
Third, cells must establish appropriate function relations with other cells
Developing neurons accomplish these three things in five phases:
oInduction of the neural plate
oNeural proliferation
oMigration and aggregation
oAxon growth and synapse formation
oNeuron death and synapse rearrangement
Induction of the neural plate
oThree weeks after conception, the tissue that is destined to develop into the human
nervous system becomes recognizable as the neural plate - a small patch of ectodermal
tissue on the dorsal surface of the developing embryo
oThe development of the neural plate is the first major stage of neurodevelopment in all
vertebrates and is induced by chemical signals from an area of the underlying mesoderm
layer - an area consequently referred to as an organizer
oTissue taken from the dorsal mesoderm of one embryo and implanted beneath the
ventral ectoderm of another embryo induces the development of an extra neural plate on
the ventral surface of the host
oCells of the neural plate are often referred to as embryonic stem cells - stem cells are
cells that meet two specific criteria:
They have an almost unlimited capacity for self-renewal if maintained in an
appropriate cell culture
They have the ability to develop into many different kinds of cells - they are
either totipotent, pluripotent, or multipotent
oWhy do stem cells have an almost unlimited capacity for self-renewal? When stem cells
divide, two different daughter cells are created: one that develops into some type of body
cell and another one that develops into another stem cell
oSince errors accumulate over time and disrupt the process, stem-cell cultures do not last
forever
Neural proliferation
oOnce the lips of the neural groove have fused to create the neural tube, the cells of the
tube begin to proliferate - this neural proliferation does not occur simultaneously or equally
in all parts of the tube
oMost cell division in the neural tube occurs in the ventricular zone - the region adjacent
to the ventricle
oThe complex pattern of proliferation is in part controlled by chemical signals from two
organizer areas in the neural tube: the floor plate, which runs along the midline of the
ventral surface of the tube, and the roof plate, which runs along the midline of the dorsal
surface of the tube
Migration and aggregation
oMigration: once cells have been created through cell division in the ventricular zone of
the neural tube, they migrate to the appropriate target location. During this period, the cells
are still in an immature form, lacking the processes that characterize mature neurons. The
two major factors which govern migration are time and location. Radial migration proceeds
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
First, cells must differentiate; some must become muscle cells, some must become multipolar neurons, some must become glial cells, and so on. Second, cells must make their way to appropriate sites and align themselves with the cells around them to form particular structures. Third, cells must establish appropriate function relations with other cells. Developing neurons accomplish these three things in five phases: o. Induction of the neural plate: neural proliferation, migration and aggregation, axon growth and synapse formation, neuron death and synapse rearrangement. Three weeks after conception, the tissue that is destined to develop into the human nervous system becomes recognizable as the neural plate - a small patch of ectodermal tissue on the dorsal surface of the developing embryo o. Tissue taken from the dorsal mesoderm of one embryo and implanted beneath the ventral ectoderm of another embryo induces the development of an extra neural plate on the ventral surface of the host o.
