BISC439 Chapter Notes - Chapter 13: Motor Neuron, Smoothened, Anatomical Terms Of Location
16 Feb 2017
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Neurulation: neural plate rolls into a tube tube sinks into the embryo epidermal ectoderm overlays embryo. Neural induction: a process in which the nervous system is formed. Spemann organizer: experiment: small piece of dorsal blastopore lip (dbl) was grafted onto newt embryos. Resulted in conjoined twins: dbl = organizer. Xenopus laevis: african frog: same experiment as spemann, different results: ectoderm differentiated into epidermis, factors expressed in dbl act as neural inducers. Inducer molecules in vertebrates: noggin, chordin, follistatin, cerberus, receptor: bone morphogenetic proteins (bmps) Default model for neural induction: in the dorsal ectoderm organizer induces neural tissue by inhibiting bmps, in the ventral ectoderm epidermis develops while in presence of bmps, neural tissue grows until anti-neuralizing signals are present. Wnt gradient: establishes dorsal identity in embryos, induces neural tissue. Induces expression of chordin, noggin, follistatin, xnr3, and cerberus: overexpression antagonizes anterior development, promotes posterior development in some animal embryos, head organizer expresses wnt inhibitors.
