Sex differences in the corpus callosum of Macaca fascicularis and Pan troglodytes.
Item
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Title
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Sex differences in the corpus callosum of Macaca fascicularis and Pan troglodytes.
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Identifier
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AAI3024765
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identifier
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3024765
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Creator
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Broadfield, Douglas C.
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Contributor
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Adviser: Jeffrey T. Laitman
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Anthropology, Physical | Biology, Neuroscience
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Abstract
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As the primary commissure in the brain, the corpus callosum has been an area of intense investigation in humans. Further, studies in humans have shown that this structure is sexually dimorphic. While the extent and meaning of sexual dimorphism in the human corpus callosum has been investigated, what this structure is like in our closest relatives, the living apes, has not been approached. This dissertation investigates whether sex differences are present within two primate species, Pan troglodytes and Macaca fascicularis, addressing several issues important to neurology, paleoneurology, and human evolution.;The corpus callosum was examined morphologically and histologically in two different primate species. In the morphological phase, the midsagittal area of the corpus callosum was examined in Pan troglodytes (12 females, 11 males) and Macaca fascicularis (20 females, 20 males). Measurements included total callosal midsagittal area and area measurements of callosal regions (splenium, isthmus, anterior and posterior midbody, genu). Two techniques were used to divide the corpus callosum into regions, a radial-line method and a straight-line method. For both methods, the area of the corpus callosum and each region was calculated to assess statistically significant differences in absolute area and relative callosal area between males and females.;In the second phase the most posterior one-fifth of the corpus callosum, the splenium, was examined in Macaca fascicularis (2 females, 2 males) and Pan troglodytes (1 male, 1 female) in order to elucidate its axonal composition. The splenium of each individual was thin sectioned (0.5mum), stained with toluidine blue, and examined using light microscopy (100x).;The results obtained from the morphological and histological aspects of this dissertation demonstrate that there is not a statistically significant difference between males and females of Pan troglodytes and Macaca fascicularis with regard to total and regional midsagittal area of the corpus callosum; or with regard to axon density/100mum 2, overall axon numbers, or within any of the axonal diameter classes in the splenium of the corpus callosum in either species. These results strongly suggest that dimorphism of the brain and corpus callosum arose later in hominin evolution, possibly not until the arrival of Homo sapiens.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
