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Gradual Appearance of a Regulated Retinotectal Projection Pattern in Xenopus laevis

O'Rourke, Nancy A. and Fraser, Scott E. (1989) Gradual Appearance of a Regulated Retinotectal Projection Pattern in Xenopus laevis. Developmental Biology, 132 (1). pp. 251-265. ISSN 0012-1606. http://resolver.caltech.edu/CaltechAUTHORS:20160414-144014139

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Abstract

The topographic projection pattern formed by the retinal ganglion cell axons in the tectum of the lower vertebrate appears to require positional cues that guide the optic nerve fibers to their appropriate targets. One approach to understanding these positional cues or “positional information” has been to investigate changes in the pattern of the retinotectal projection after surgical manipulation of the embryonic eyebud. Analysis of these apparent changes in the patterns of positional information in the eye, termed “pattern regulation,” may provide clues to both the nature of positional information and the mechanisms by which it is assigned to cells in the eyebud. Here we examine pattern regulation in the Xenopus visual system following the replacement of the temporal half of a right eyebud with the temporal half of a left eyebud. This manipulation requires that the left half-eyebud be inverted along its dorsoventral axis. Electrophysiological maps of these compound eyes in postmetamorphic frogs reveal regulated maps; the cells in the temporal half of the NrTl eye project to the tectum with a dorsoventral polarity appropriate for their position in the host eye and not appropriate for the original positions of the grafted cells in the donor eyebud. Paradoxically, the regulated patterns are not apparent in the projections of the original grafted eyebud cells during early larval development. Using fiber-tracing and electrophysiological mapping techniques, we now show that the regulated patterns appear gradually in the projections made by peripheral retinal cells added during mid-larval development. Because the regulation occurs relatively late in development and probably only in the peripheral retinal cells, simple models of epimorphic or morphallactic regulation do not appear to fit this system. Thus, new or more complex models must be invoked to explain the phenomenon of pattern regulation in the developing visual system of Xenopus.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/0012-1606(89)90221-2DOIArticle
http://www.sciencedirect.com/science/article/pii/0012160689902212PublisherArticle
ORCID:
AuthorORCID
Fraser, Scott E.0000-0002-5739-4026
Additional Information:© 1989 Academic Press, Inc. Accepted November 22, 1988. We thank H. Fujisawa for his helpful advice on using the anterograde labeling technique and M. S. Carhart for assisting with the photography. We are grateful for comments on the manuscript provided by Drs. J. Stollberg, R. W. Wetts, and W. L. Todt. Preliminary reports of this work have appeared elsewhere (O'Rourke and Fraser, 1986e). This work was supported by grants from the NSF (BNS85-11224 and BNS86-08356) and by a McKnight Foundation Scholar's Award.
Funders:
Funding AgencyGrant Number
NSFBNS85-11224
NSFBNS86-08356
McKnight FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20160414-144014139
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160414-144014139
Official Citation:Nancy A. O'Rourke, Scott E. Fraser, Gradual appearance of a regulated retinotectal projection pattern in Xenopus laevis, Developmental Biology, Volume 132, Issue 1, 1989, Pages 251-265, ISSN 0012-1606, http://dx.doi.org/10.1016/0012-1606(89)90221-2. (http://www.sciencedirect.com/science/article/pii/0012160689902212)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66183
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Apr 2016 23:01
Last Modified:14 Apr 2016 23:01

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