Lecture 23 Flashcards
gastrulation is __
the local invagination of a subset of cells in the early embryo
gastrulation creates _ germ layers: ___
3; ectoderm, mesoderm, endoderm
ectoderm =
nervous system, epidermis
mesoderm =
notochord, bone, muscle, connective tissue, gonad
endoderm =
GI tract, respiratory tract, endocrine system, auditory system, urinary system
the initiation of neural development is critically dependent on what two processes?
gastrulation and neurulation
when the process of gastrulation is complete, the embryo will consist of __
3 germ layers (ectoderm, mesoderm, endoderm)
an important event in the process of __ is the formation of the notochord
gastrulation
the formation of the notochord ___ is very important
at the midline of the gastrulating embryo
the notochord is a __ of __ cells, which condense at the __ as ___
cylinder; mesodermal; midline; the mesoderm invaginates
the notochord extends from the __ to the __
anterior to posterior
during late gastrulation, mesodermal cells in the region of the primitive streak form the __
notochord
the notochord is a critical feature - it directs the __ (secretes __)
formation of the nervous system; secretes inductive factors
the layer of ectoderm that lies right above the notochord is called the __ which is tiny but gives rise to __
neuroectoderm; the entire nervous system
the notochord defines the __ of the embryo; lays out the __ for the entire body
midline of the embryo; symmetry
primitive pit is __; which leads to the __, leads to the __
the very first dent; leads to the primitive streak, which leads to the notochord
the notochord induces the neuroectoderm to ___
differentiate into precursor cells that thicken and become the neural plate
the neural plate is just the __ in another phase/state
neuroectoderm
cells from the __ and the __ send chemical/molecular signals to the neuroectoderm, which causes a subset of cells to __…..this process intiates __
notochord and primitive streak; differentiate into neural plate precursor cells; neurulation
the thickening is called the __
neural plate
the lateral margins of the neural plate begin to __, which transforms the plate into a __
fold upward; tube
the cells within the neural tube give rise to __
the brain and spinal cord
those neuroectoderm precursor cells are the __. they are __ and have the capacity to __
progenitors of the neural tube; stem cells; give rise to any cell class found in the mature nervous system
neural crest cells are at the border of the __ and the __
neural plate and the non-neural ectoderm
neural crest cells are a __ group of cells and are unique to __
temporary; vertebrates
3 examples of what neural crest cells give rise to
cartilage, bone, smooth muscles
what are the “neural stem cells”?
the neuroectodermal precursor cells
how are neural stem cells different than embryonic stem cells?
they cannot give rise to ANYTHING, it has to be some neural tissue
neural stem cells divide to produce __
more precursor cells
neural stem cells give rise to __
neurons, astrocytes, oligodendrocytes, glia, etc.
what do neural stem cells depend on to determine what they become?
the local environment (molecular cues)
the neural tube also contains specialized epithelial-like cells called the __
floorplate
the floorplate secretes molecular signals that __
specify position and fate of neural progenitors
are all cells in the neural tube self-renewing?
no
neural tube also gives rise to a subset of progenitor cells called the __
neural crest