ZOO 2090 Lecture Notes - Lecture 4: Germ Layer, Neural Crest, Organogenesis

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Fred Laberge

Document Summary

Describe basic germ layers & 4 basic tissue types they generate concepts of differentiations and organogenesis timing of developmental events and how play role in phylogenetic change. Cleavage: from zygote to multicellular hollow blastula. Gastrulation and neurulation: formation of germ layers. Differentiation and organogenesis: from germ layers to organs: cleavage: from zygote to multicellular hollow blastula, gastrulation: formation of germ layers, neurulation: formation of neural tube. Differentiation: form germ layers to basic tissues: 4 primary tissues: Placodes: arise from thickenings of the surface ectoderm and cavitation, give rise to sensory organs and receptors, note that the vertebrate head derives mostly from neural crest and placodes. Maturation juvenile sexually mature adult (direct development) larva metamorphosis sexually mature adult larva growth/reproduction as larva. Heterochrony change in the timing of developmental events across generations links otogeny with phylogeny. Ernst haeckel biogenetic law: ontogeny recapitulates phylogeny: however, there is no correspondence between descendent embryos and ancestor adults.