Brain Cytoarchitecture in a Large Grazing Marsupial, Rufous Wallaby Thylogale billardieri. Cindy D. Knaff, under the direction of Dr. John I. Johnson, Radiology RUFOUS WALLABY OLFACTORY DOMESTIC SHEEP Thylogale billardieri SYSTEM Ovis aries turs Results Visible lamination in cell groups within the brain is one indicator of relatively well developed systems. Sections from both species show several visibly laminated brain regions subserving olfaction, vision, and audition, as well as a large extent of laminated cerebral isocortex. The OLFACTORY BULBS in both species are large and show a high degree of visible lamination. From http: //brainmuseum. org/Specimens/marsupalia/ rufwallaby/index. html Original photograph, John I. Johnson ABOVE: Coronal view of the olfactory bulb and stalk. The VISUAL SUPERIOR COLLICULI are larger than the AUDITORY INFERIOR COLLICULI in both species, and show visible lamination. This is typical of herbivorous “prey species” who must keep a watch for predators while still far away. VISUAL AND AUDITORY SYSTEMS ABOVE: Sagittal view of the superior and inferior colliculi. VISUAL SYSTEM The VISUAL LATERAL GENICULATE NUCLEUS shows visible lamination in both species. Sheep have three distinct laminae in each lateral geniculate nucleus (Clarke, et al. , 1988), while Rufous Wallabies have 7 or 8 laminae (Sanderson et al. , 1984, 1987), some of which are visible here. kog ABOVE: Six standard views of the intact brains. From http: //brainmuseum. org/Specimens/marsupalia/rufwallaby/index. html From http: //brainmuseum. org/Specimens/artiodactyla/sheep/index. html The AUDITORY DORSAL COCHLEAR NUCLEUS shows distinct lamination in both species. This nucleus has recently been shown to have a cerebellum-like function (Oertel & Young, 2004). Introduction Brain evolution can be seen through comparative neurology. Wallabies, large grazing marsupials, provide opportunities to study evolutionary convergences with brains of independently evolved brains of large grazing placental mammals, from a separate branch of mammalian radiation. We have analyzed the internal structure of the brains of Rufous Wallabies Thylogale billardieri, in direct comparison with their counterpart structures in Domestic Sheep Ovis aries. ABOVE: Sagittal view of the lateral geniculate nucleus and optic tract AUDITORY SYSTEM Conclusions These particular parallel hyperdevelopments in maximally distant related species appear to be related to environmental adaptations rather than to phylogenetic relationships. Procedures Sections of brains from museum collections were examined for evidence of specializations related to herbivorous grazing behavior. These wallaby and sheep brains were dehydrated, embedded in nitrocellulose (celloidin), sectioned at 35 um intervals and were stained with thionine, a standard Nissl staining procedure, to show distributions of neuronal cell bodies. . REFERENCES Clark PG, Martin KA, Rao Vm, Whitteridge D. The dorsal lateral geniculate nucleus of the sheep and its retinal connections. Q J Exp Physiol. 1988 May: 73(3): 295 -304. Oertel D. Young ED, What’s a cerebellar circuit doing in the auditory system? Trends Neurosci. 2004 Feb: 27(2): 104 -10. ABOVE: Horizontal view of the dorsal and ventral cochlear nuclei. Sanderson KJ, Haight JR, Pettigrew JD. The dorsal lateral geniculate nucleus of macropodid marsupials: cytoarchitecture and retinal projections. J Comp Neurol. 1984 Mar 20: 224(1): 85 -106. Sanderson KJ, Nelson JE, Crewther DP, Crewther SG, Hammond VE. Retinogeniculate patterns in diprotodont marsupials. Brain Behav Evol. 1987: 30(1 -2): 22 -42 See the atlases of the brains of dolphins, sheep, humans and axolotls at http: //www. brains. rad. msu. edu, http: //brainmuseum. org or http: //www. user/brains/atlases msu. edu A similar atlas of the brains of rufous wallabies is in preparation for these sites. Poster design, adviser and printer Gearl Diggs, Radiology Dept. Michigan State University Supported by The Division of Integrative Biology and Neuroscience of THE NATIONAL SCIENCE FOUNDATION grants IBN 0131267, 0131028, 0131826.
Скачать презентацию Brain Cytoarchitecture in a Large Grazing Marsupial Rufous
00b4c8d771903947b1d57c9c1d729c48.ppt