Friday, April 9, 2010
Diffferences in embryos
In chapter 3 on pages 73-80, Mr. Coyne explains the stages that happen from an embryo to the full organism. He explains that "all vertebrates begin development in the same way [but] as development proceeds, different species begin to diverge"(73). Using Why evolution is true, the Campbell book, and outside sources, provide a description of an animal from their embryo stage to when they are born. Explain how, when, and why certain organs and structures form in the animal. Also explain the similarities and differences of the development process of your chosen animal to other animals.
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In the beginning of the embryonic stage, all vertebrates look similar. Humans aren’t much different from the rest of embryonic vertebrates. Humans begin resembling the form of an embryonic fish. “Lets start with that fishy fetus of all vertebrates--- limbless and sporting a fish like tail. Perhaps the most striking fishlike feature is a series of five to seven pouches, separated by groves, that lie on each side of the embryo near its future head. These pouches are called the branchial arches…contains tissue that develop into nerves, blood vessels, muscles, and bone or cartilage” (74). These aches develop into specific sections of the organisms such as limbs and organs. In humans, the branchial arches develop into the critical systems in our body. These include the skeletal, nervous, and respiratory systems by generating the organs necessary such as lungs, heart, and bone. When comparing our developmental process with lets say a fish, we notice many differences. For example our branchial arches alter its form to generate lungs and heart while a fishes would stop short and generate gills and a heart instead.
ReplyDeleteThe embryonic development links into the concept of evolution. When a human embryo undergoes its transformation, the embryo must travel through its evolutionary history of gradual change to preserve the developmental plan it was based off of. In our case, the human embryo would have to go through the embryonic plans of the fish, then amphibian, then reptile, and eventually us…mammals.