Garstang's Paedomorphosis Hypothesis
Walter Garstang - Wikipedia
Chapter 23: Question 10 - Zoology
Atherosclerotic lesions also develop innormolipidemic rabbits as a result of repeated, or continuousintimal injury by catheters or balloons, or by nitrogen exposure().The pig is a very good model to study CVD as it hasa human-like cardiovascular anatomy ().
The larvae of the invertebrate chordates (tunicates and amphioxus) are secondary larvae whose relation to the primary dipleurula-type larvae of echinoderms and hemichordates is somewhat obscure. Past authorities have argued that chordates actually derive from motile larvae that have evolved to become sexually mature (paedomorphosis). One such proposal, more specific in its predictions than most, is due to Walter Garstang: he noted the topological similarity between dipleurula ciliary bands (which have their own innervation) and chordate neural plate, and suggested that the latter actually derive from the former. While there is as yet no convincing evidence that chordates are directly derived from the body of a dipleurula-type larva, the core of the idea, that there is continuity in the neurogenic tissues, has some appeal. It is a surprisingly parsimonious way of deriving a characteristic chordate structure, the neural tube, whose origin is otherwise unexplained.
garstang’s theory | All you need is Biology
Third, all four remaining features (a notochord, a dorsal neural tube, myotomes and a postanal tail) are deeply associated with the evolution of FT larvae, a new larval type that swims using a beating tail. The occurrence of FT larvae within deuterostomes (not by changing the form of dipleurula or auricularia-like larvae) is therefore critical to understanding chordate origins. It should be emphasized that all structures are formed through embryogenesis until larval formation. This suggests that an embryological comparison between non-chordate (e.g. acorn worms) and chordate deuterostomes (e.g. lancelets) might be the first step to elucidate developmental mechanisms of chordate origin, as structures corresponding to a dorsal neural tube and notochord never develop in acorn worm embryos. The postanal tail is likely to be associated with formation of the so-called ‘tailbud’, which probably functions as an organizer for tail elongation in chordate embryos . Therefore, it is wiser to ask how these structures are newly formed in chordate embryos rather than to seek possible homologies with other structures of acorn worm embryos and larvae.
What is Gastrang's hypothesis? What does it state? | …
21/07/2011 · Walter Garstang: a retrospective
Northwest Missouri State University
Walter Garstang FLS FZS ..
Neoteny (/ n iː ˈ ɒ t ɪ n i / / n ..
Explain this hypothesis
The an cestry of the vertebrates was the ..
"I have always been impressed by the quick turnaround and your thoroughness. Easily the most professional essay writing service on the web."
"Your assistance and the first class service is much appreciated. My essay reads so well and without your help I'm sure I would have been marked down again on grammar and syntax."
"Thanks again for your excellent work with my assignments. No doubts you're true experts at what you do and very approachable."
"Very professional, cheap and friendly service. Thanks for writing two important essays for me, I wouldn't have written it myself because of the tight deadline."
"Thanks for your cautious eye, attention to detail and overall superb service. Thanks to you, now I am confident that I can submit my term paper on time."
"Thank you for the GREAT work you have done. Just wanted to tell that I'm very happy with my essay and will get back with more assignments soon."