Embryology - Biology 104, Spring 2006 - Albert Harris and Corey Johnson
Review Questions for Second ExamHow does the cell decide which direction to cleave? Why is it so consistent from one frog to the next (meridional, meridional, equatorial)? The centrioles of the zygote come from which parent? What are the descriptive terms for describing the amount and location of yolk within an embryo? What did Spemann demonstrate about the potential of the zygote by temporarily separating two ends of a newt zygote and then allowing development to proceed, resulting in development of two attached embryos? What about the nuclear transfer of an adult frog nucleus to an egg? What's unique about bird cell divisions? What's unique about that of mammals? Hans Spemann won the Nobel Prize in 1935 for his work with Hilde Proschhold (Mangold). What did they do/discover? The organizer orchestrates what process? What cells descend from the organizer? What structure is induced from these cells? Heat-killed organizers could be implanted in host embryos and result in the same effect as live tissue. Speculate as to how such an Òun-deadÓ tissue could elicit such an effect. See any connection with what Roux did? What is induction? What induces mesoderm to form between endo- and ecto-derm? What is the marginal zone? Without the nieukoop center, what type of symmetry does the amphibian embryo have? What is fate mapping and how is it accomplished? Contrast newt and Xenopus gastrulation. What's that yolk plug thing? Through what morphogenetic movement does the A-P axis lengthen during gastrulation? Where do the bottle cells end up at the end of gastrulation? Where are they found at the onset of gastrulation? What are the area pellucida and area opaca? What happens at the primitive streak (what morphogenetic movement)? Henson's node is the functional equivalent of what structure in amphibians? What cells are derived from it? What causes the regression of the node? What's so great about zebrafish? Advantages and disadvantages? Who was at one time the leading fish embryologist, expert on cell movements in embryos, and PhD advisor of Dr. Harris? What is the fate of the following tissues in the fish: enveloping layer, deep cells, YSL What is the embryonic shield? Gastrulation involves what morphogenetic movement in fish? Neurulation accomplishes the segregation of what three tissues? WhatÕs the major difference between primary and secondary neurulation? Does cavitation only happen in secondary neurulation? Failure of the neuropore to close can result in what birth defects? How do fish form their neural tubes? How do cells of the neural tube acquire their identity? What would you expect to happen to the fate of neurons if you removed the neural notochord and floorplate? Is Sonic Hedgehog (Shh) a stupid name for a gene? What affect does Shh have on neural cells? What about BMP? What are the 3 major divisions of the brain? How are they formed (physically)? WhatÕs a rhombomere? What might hox genes do? Saxen and Toivonen implanted guinea pig pieces into blastocoels and caused various structures to be induced; what would you expect would happen to hox gene expression in an experiment where posterior structures are induced? Would posterior hox genes be expressed where they donÕt belong? What is co-linearity? How do somites form along the A-P axis? What are the three divisions of somites and what structures do they become? Where does neural crest come from, and where does it go (specifically, what cells come from neural crest that lie near the NT)? WhatÕs the relationship between embryological dermatomes from and physiological dermatomes? Describe vertebrae formation from somites. What structures come from the intermediate mesoderm? Somatic mesoderm? Splanchnic mesoderm? What substance is wrapped around the notochord? How might this add to the rigidity of the structure in amphibians and fish? What types of animals form extraembryonic membranes? Which of these are amniotes? What does the yolk sac do? Which of the 4 extraembryonic membranes forms from embryonic hindgut? What layers of the extraembryonic tissues contribute to which membranes? If the inner cell mass somehow got separated to form two ICMÕs, would the resulting twins share the same chorion? What if two separate blastocysts formed from one zygote? Would they share any membranes? What if 2 primitive streaks formed in the same ICMÉ would they share the same amnion? From what layers do humans form their Chorion? Amnion? Yolk Sac? Mice develop strangely, donÕt they?
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