Bio exam 2 - Christine Yu Dr. Kennett Bio 362 6 December...

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Christine Yu Dr. Kennett Bio 362 6 December 2010 1. The human caudate nucleus is a component of the striatum, along with the putamen and the globus pallidus. The striatum is a part of the brain located within the basal ganglia. The human caudate nucleus develops from the location of the tissue from the neuroblasts from the striatal ridge of the telencephalon. The ectoderm thickens to become the neural plate while the neural folds rise and fuse to form the neural tube. The neural tube forms the telencephalon, which expands rapidly due to cell proliferation. Gradually the cells stop divding and differentiate to become neurons and glial cells which are the main cell components. During development, as the telencephalon expands, the hemispheres of the brain are separated and fused. The corticofugal fibers of the internal capsule divides the caudate nucleus from the other structures of the corpus striatum. While the hemispheres of the brain grow posteriorly, the body of the caudate nucleus forms the tail of the nucleus, following the wall of the lateral ventricle as it, too, develops. During development, the ectoderm specifically forms the epidermis and the neural plate which requires signals from the mesoderm germ layer. At the beginning of gastrulation, mesodermal cells move through the blastopore and form a layer between the ectoderm and endoderm germ layers, becoming the notochord. The notochord produces a diffusible signal that allows the ectodermal cells to respond by developing into the neural plate. The mesoderm converts the ectoderm into neural tissue. In order for the caudate nucleus to form normally from the ectoderm, proper development of the structures are essential in forming the pathways for normal development. One question that is applicable to our world today is the affect of drug abuse on the development of the human caudate nucleus. It would be interesting to see the difference in the cellular and molecular mechanisms that psychostimulants have on the development of the human caudate nucleus. One question that remains is the reason for the rapid expansion of brain volume. It is thought to be caused by positive cerebrospinal fluid pressue exerted against the walls of the neural tube. 2. The retina arises from the neural tube which is formed by the neuroectoderm. It is formed through cranial ectodermal placodes which interact with the neural tube. During gasturation, the mesoderm and endoderm germ layers work together with the ectoderm to form the lens. The optic vesicle, extending from the diencephalons, turns into the optic cup which cells create melanin pigmented retina. The outer wall of the optic cup forms the pigment retina, while the inner wall of the optic cup forms the neural retina. The neural retina is formed from the proliferation of inner layer cells which generate glia, ganglion cells, interneurons, and light-sensitive photoreceptor neurons. The transcription factors, Six3, Pax6, and Rx1, are expressed together in the neural plate which inform the specific region of the neural ectoderm of becoming the retina.
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Bio exam 2 - Christine Yu Dr. Kennett Bio 362 6 December...

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