This work is intended to increase our understanding of the development of the optic chiasm and tract. The projection from the retina to the brain is essential for sight, and the highly ordered nature of the axons' trajectories and terminations are key to the formation of connections that make spatial vision possible. The retinofugal projection is thought to resemble all central nervous system projections, so a study of its development relates to central nervous system development generally. Developmental disorders can not be understood without knowledge of the normal developmental processes, and this proposal is intended to reveal them. It is an anatomical study in which light and electron microscopy and immunocytochemistry are used to study three key players. First, the formation of the projection is initiated by a small set of """"""""pioneer"""""""" axons originating from 5-10 ganglion cells in the retina; experiments in this proposal should elucidate their role in leading the vastly more numerous axons that follow them. Second, the retinal axons pass alongside a pre-existing tract in the brain on their way to the optic tectum; the work proposed here will reveal more about that pre-existing tract and about its role in guiding the growing axons. Third, a structurally distinct zone alongside the pre-existing tract has recently been discovered, and this is where the retinal axons grow; the work here will investigate the importance of that zone in guiding the axons and assess the generality of such a structure for other cases of axonal guidance. Most of the work is carried out in the embryonic zebrafish (Brachydanio rerio), chosen because of its technical advantages and because early development is thought to be very similar in all vertebrates. Where possible, the conclusions will be checked in other vertebrates: frog, chick, and mouse.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY000168-26
Application #
2157760
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1978-05-01
Project End
1998-12-31
Budget Start
1996-03-01
Budget End
1998-12-31
Support Year
26
Fiscal Year
1996
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Li, Z; Hu, M; Ochocinska, M J et al. (2000) Modulation of cell proliferation in the embryonic retina of zebrafish (Danio rerio). Dev Dyn 219:391-401
Li, Z; Joseph, N M; Easter Jr, S S (2000) The morphogenesis of the zebrafish eye, including a fate map of the optic vesicle. Dev Dyn 218:175-88
Hu, M; Easter, S S (1999) Retinal neurogenesis: the formation of the initial central patch of postmitotic cells. Dev Biol 207:309-21
Masai, I; Heisenberg, C P; Barth, K A et al. (1997) floating head and masterblind regulate neuronal patterning in the roof of the forebrain. Neuron 18:43-57
Cameron, D A (1995) Asymmetric retinal growth in the adult teleost green sunfish (Lepomis cyanellus). Vis Neurosci 12:95-102
Easter Jr, S S; Burrill, J; Marcus, R C et al. (1994) Initial tract formation in the vertebrate brain. Prog Brain Res 102:79-93
Rowe, M P; Engheta, N; Easter Jr, S S et al. (1994) Graded-index model of a fish double cone exhibits differential polarization sensitivity. J Opt Soc Am A Opt Image Sci Vis 11:55-70
Burrill, J D; Easter Jr, S S (1994) Development of the retinofugal projections in the embryonic and larval zebrafish (Brachydanio rerio). J Comp Neurol 346:583-600
Cameron, D A; Easter Jr, S S (1993) The cone photoreceptor mosaic of the green sunfish, Lepomis cyanellus. Vis Neurosci 10:375-84
Easter Jr, S S; Ross, L S; Frankfurter, A (1993) Initial tract formation in the mouse brain. J Neurosci 13:285-99

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