Roles of the telencephalic cells and their chondroitin sulfate proteoglycans in delimiting an anterior border of the retinal pathway.
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.
Ichijo
H
H
Department of Anatomy, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. ichijo@md.tsukuba.ac.jp
Kawabata
I
I
D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002642:Chick Embryo; D019765:Chondroitin ABC Lyase / Q000008:administration & dosage / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism* / Q000494:pharmacology; D002809:Chondroitin Sulfates / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015194:Diffusion Chambers, Culture; D007276:Injections, Intraventricular; D012160:Retina / Q000166:cytology / Q000196:embryology*; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000187:drug effects; D013347:Subcellular Fractions / Q000737:chemistry; D013687:Telencephalon / Q000737:chemistry / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D014795:Visual Pathways / Q000166:cytology / Q000187:drug effects / Q000196:embryology*
D002241:Carbohydrates; D011508:Chondroitin Sulfate Proteoglycans; D017077:Culture Media, Conditioned; C038142:chondroitin sulfate glycosaminoglycan; D002809:Chondroitin Sulfates; D019765:Chondroitin ABC Lyase