Early Steps in the Formation of Neural Tissue in Ascidian Embryos
[摘要] Ascidiansaresimpleinvertebratechordateswhoselineagedivergedfromthatofvertebratesatthebaseofthechordatetree.Theirlarvaedisplayatypicalchordatebodyplan,butarecomposedofaremarkablysmallnumberofcells.Ascidiansdevelopwithaninvariantcelllineage,andtheirembryoscanbeeasilyexperimentallymanipulatedduringthecleavagestages.Theirlarvalnervoussystemisorganisedinasimilarwayasinvertebratesbutiscomposedoflessthan130neuronesandaround230glialcells.Thisremarkablesimplicityoffersanopportunitytounderstand,atthecellularandmolecularlevels,theontogenyandfunctionofeachneuralcell.Here,wefirstreviewtheorganisationoftheascidiannervoussystemanditslineage.Wethenfocusonthecurrentunderstandingoftheprocessesofneuralspecificationandpatterningbeforeandduringgastrulation.Wediscusstheseadvancesinthecontextofwhatiscurrentlyknowninvertebrates.
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[效力级别] [学科分类] 生物科学（综合）
[关键词] ascidians;chordates;evolution;nervous system;neural induction;embryo;development;neurone;Otx;BMP;FGF;proteases;CNS;PNS;placodes;neural crest [时效性]
