The Journal of Neuroscience, December 1, 2001, 21(23):9304-9314
Roles of the Telencephalic Cells and their Chondroitin Sulfate
Proteoglycans in Delimiting an Anterior Border of the Retinal
Pathway
Hiroyuki
Ichijo and
Izumi
Kawabata
Department of Anatomy, Institute of Basic Medical Sciences,
University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
The axons of the retinal ganglion cells run on the
diencephalotelencephalic boundary on their way to the tectum; however, they do not invade the telencephalon anteriorly. To investigate the
mechanisms that prevent the retinal axons from entering the telencephalic territory, the effects of the telencephalic cells were
examined on the outgrowth of the retinal axons in vitro; the retinal outgrowth was selectively inhibited by the cellular substrate derived from the telencephalon. The responsible factor for
the selective inhibition was, furthermore, found in the telencephalic membranes and the fraction of peripheral membrane molecules from the
telencephalon. Because the inhibitory effect was destroyed by
chondroitinase ABC but not by heat, this inhibition was
attributable to the carbohydrate chains of chondroitin sulfate
proteoglycans (CSPGs) adhering to the membranes of the telencephalic
cells. To understand the function of the telencephalic CSPGs on the
retinal pathfinding in vivo, their carbohydrate chains
[chondroitin sulfate glycosaminoglycan (CS-GAG)] were removed from
the embryonic brains by intraventricular injection of chondroitinase
ABC; the removal of CS-GAG resulted in an anterior enlargement of the
optic tract. The results indicate that the telencephalic cells delimit
the anterior border of the optic tract with their CSPGs and prevent the
retinal axons from aberrantly entering the anterior territory.
Key words:
axon guidance; pathfinding; retinotectal projection; optic tract; retinal ganglion cell; chondroitin sulfate proteoglycan; telencephalon
Copyright © 2001 Society for Neuroscience 0270-6474/01/21239304-11$05.00/0