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Unformatted text preview: ion-speciﬁc behaviors Adapted from Gilbert 9e, Fig. 7.10 Gastrulation involves region-speciﬁc behaviors Leading edge mesoderm:
directed migration blastocoel
roof migrating cells Leading edge cells migrate along the blastocoel
roof, where oriented ﬁbronectin ﬁbrils are found.
courtesy Ray Keller Leading edge mesoderm undergoes directed migration
migration at the
front edge of the
involuting material see Gilbert, 9e, Fig. 7.10 Leading edge mesoderm cells migrate via lamellipodia
anterior lamellipodia posterior
courtesy Ray Keller The axolotl, Ambystoma mexicanum is
useful for studying leading edge mesoderm Axolotls are interesting because the exhibit neoteny, i.e., they become
reproductively mature while maintaining juvenile (larval) characteristics.
In addition, they are useful for studying leading edge migration during
gastrulation. The blastocoel roof has oriented ﬁbronectin ﬁbrils Gilbert, 4e, Fig. 4.25
Fibronectin ﬁbrils have an overall orientation along the anteriorposterior axis (i.e. the direction leading edge cells normally migrate) Antibodies can be used to disrupt
into the blastocoel
disrupt binding of cells
to ﬁbronectin. Kalthoff, 2e, Fig. 11.24 Involution normally occurs in axolotl embryos Involution normally pushes the blastocoel (bc) out of the way,
forming the archenteron (ar), and covering the yolk plug (yp)
Gilbert, 4e, Fig. 4.26 Disrupting attachment to ﬁbronectin blocks
not displaced mesoderm (failed
to involute) endoderm
not covered Involution is blocked in embryos injected with anti-FN antibodies
Conclusion: FN is needed for mesoderm migration
Gilbert, 4e, Fig. 4.26...
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This note was uploaded on 11/08/2013 for the course ZOOLOGY 470 taught by Professor Hardin during the Fall '12 term at Wisconsin.
- Fall '12