Lecture 6 Flashcards
what are the 3 germ layers from outermost to inner most?
ectoderm, mesoderm, endoderm
what does the ectoderm give rise to
the epidermis and neural tissue
what does the mesoderm give rise to
skeletal muscle, skeleton, connective tissues, dermis of the skin, urogenital and cardiovascular systems
what does the endoderm give rise to
digestive and respiratory systems and epithelial linings to most tubes and structures
what occurs in the mesoderm of an embryo
it secretes factors that facilitate determination of a small number of ectodermal cells to become neural cells. the remainder become epidermal cells
what are the steps of development of the nervous system
- determination
- proliferation
- survival
- migration
- differentiation
what happens in determination
neural precursor cells originate from the ectoderm germ layer of the embryo
How does ectoderm layer develop into epidermal cells in differentiation
cell-to-cell contact, absence of underlying mesoderm, and/or under guidance of BMPs
how do neural precursors develop instead of epidermal cells in differentiation
if dissociated or cultured in specific piece of the mesoderm, or by release of neural inducers from underlying mesoderm
what is the BMP pathway
binding of BMP to their receptor initiates phosphorylation and activation of the smad1:smad4 pathway which activates transcription and activation of neural gene set
how do neural inducers work
by binding to BMP preventing it from binding to its receptor which enables activation and transcription of genes required for development of the ectodermal cells into neural precursors
how can neurons be “rescued” from dying off?
- transplanting additional limb onto embryo
- chem factors from tissue culture experiments
- serum added to cell cultures
- conditioned media
- NGF
Explain how chemical factors from tissue culture experiments saved neurons
factors released from the organs could support survival and growth of the neurons
explain how conditioned media from cell culture experiments saved neurons
media taken from one set of cultures and fed to a separate set of cultures showed that these factors released by the cells diffused into the media and could be depleted when used up by other cells
explain NGF
shown to be sufficient to support neuronal cell survival and axonal outgrowth, the effect was specific for neuronal cell type and worked in a concentration dependent manner
