Directed early axonal outgrowth from retinal transplants into host rat brains

Mark Hankin, Raymond D. Lund

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Axons from retinae transplanted to the brain stem of neonatal rats exhibit two patterns of outgrowth that can be experimentally uncoupled from each other depending upon the location of the graft. Retinae placed close to the surface of the rostral brain stem (as much as 5 mm from the tectum) emit axons that project toward the superior colliculus along the subpial margin of the rostral brain stem. In contrast, axons from grafts embedded deep within the midbrain parenchyma project through the neuropil directly to the overlying superior colliculus, as long as the retina is within about 1 mm of the tectal surface. The present study shows that, as long as the retina is located outside the superior colliculus, and regardless of whether the axons derive from grafts in subpial or intraparenchymal locations, the earliest projections are oriented towards the superior colliculus. We have also found, however, that axons from retinae transplanted directly onto the superior colliculus can form projections that extend along the subpial margin away form the tectum. There are several major conclusions that may be drawn from these observations. First, the final tectopetal, transplant‐derived projection does not result from the reorganization of an initially random outgrowth but is directed from the start toward an appropriate region of termination. Second, it appears that the interaction of retinal axons with a primary target alters the ability of the growth cone to respond to directional cues along the optic tract. Thus, although adding support to the proposal that optic axons attain the superior colliculus through an interaction involving substrates distributed along the optic tract and diffusible factors originating in the target region, it is increasingly clear that such interactions are likely to be complex and hierachical.

Original languageEnglish (US)
Pages (from-to)1202-1218
Number of pages17
JournalJournal of Neurobiology
Volume21
Issue number8
DOIs
StatePublished - Jan 1 1990
Externally publishedYes

Fingerprint

Superior Colliculi
Axons
Transplants
Retina
Brain
Brain Stem
Growth Cones
Aptitude
Neuropil
Mesencephalon
Cues

ASJC Scopus subject areas

  • Neuroscience(all)
  • Cellular and Molecular Neuroscience

Cite this

Directed early axonal outgrowth from retinal transplants into host rat brains. / Hankin, Mark; Lund, Raymond D.

In: Journal of Neurobiology, Vol. 21, No. 8, 01.01.1990, p. 1202-1218.

Research output: Contribution to journalArticle

@article{279caa1fb73043d3bd6b81cbacad55d2,
title = "Directed early axonal outgrowth from retinal transplants into host rat brains",
abstract = "Axons from retinae transplanted to the brain stem of neonatal rats exhibit two patterns of outgrowth that can be experimentally uncoupled from each other depending upon the location of the graft. Retinae placed close to the surface of the rostral brain stem (as much as 5 mm from the tectum) emit axons that project toward the superior colliculus along the subpial margin of the rostral brain stem. In contrast, axons from grafts embedded deep within the midbrain parenchyma project through the neuropil directly to the overlying superior colliculus, as long as the retina is within about 1 mm of the tectal surface. The present study shows that, as long as the retina is located outside the superior colliculus, and regardless of whether the axons derive from grafts in subpial or intraparenchymal locations, the earliest projections are oriented towards the superior colliculus. We have also found, however, that axons from retinae transplanted directly onto the superior colliculus can form projections that extend along the subpial margin away form the tectum. There are several major conclusions that may be drawn from these observations. First, the final tectopetal, transplant‐derived projection does not result from the reorganization of an initially random outgrowth but is directed from the start toward an appropriate region of termination. Second, it appears that the interaction of retinal axons with a primary target alters the ability of the growth cone to respond to directional cues along the optic tract. Thus, although adding support to the proposal that optic axons attain the superior colliculus through an interaction involving substrates distributed along the optic tract and diffusible factors originating in the target region, it is increasingly clear that such interactions are likely to be complex and hierachical.",
author = "Mark Hankin and Lund, {Raymond D.}",
year = "1990",
month = "1",
day = "1",
doi = "10.1002/neu.480210806",
language = "English (US)",
volume = "21",
pages = "1202--1218",
journal = "Developmental Neurobiology",
issn = "1932-8451",
publisher = "John Wiley and Sons Inc.",
number = "8",

}

TY - JOUR

T1 - Directed early axonal outgrowth from retinal transplants into host rat brains

AU - Hankin, Mark

AU - Lund, Raymond D.

PY - 1990/1/1

Y1 - 1990/1/1

N2 - Axons from retinae transplanted to the brain stem of neonatal rats exhibit two patterns of outgrowth that can be experimentally uncoupled from each other depending upon the location of the graft. Retinae placed close to the surface of the rostral brain stem (as much as 5 mm from the tectum) emit axons that project toward the superior colliculus along the subpial margin of the rostral brain stem. In contrast, axons from grafts embedded deep within the midbrain parenchyma project through the neuropil directly to the overlying superior colliculus, as long as the retina is within about 1 mm of the tectal surface. The present study shows that, as long as the retina is located outside the superior colliculus, and regardless of whether the axons derive from grafts in subpial or intraparenchymal locations, the earliest projections are oriented towards the superior colliculus. We have also found, however, that axons from retinae transplanted directly onto the superior colliculus can form projections that extend along the subpial margin away form the tectum. There are several major conclusions that may be drawn from these observations. First, the final tectopetal, transplant‐derived projection does not result from the reorganization of an initially random outgrowth but is directed from the start toward an appropriate region of termination. Second, it appears that the interaction of retinal axons with a primary target alters the ability of the growth cone to respond to directional cues along the optic tract. Thus, although adding support to the proposal that optic axons attain the superior colliculus through an interaction involving substrates distributed along the optic tract and diffusible factors originating in the target region, it is increasingly clear that such interactions are likely to be complex and hierachical.

AB - Axons from retinae transplanted to the brain stem of neonatal rats exhibit two patterns of outgrowth that can be experimentally uncoupled from each other depending upon the location of the graft. Retinae placed close to the surface of the rostral brain stem (as much as 5 mm from the tectum) emit axons that project toward the superior colliculus along the subpial margin of the rostral brain stem. In contrast, axons from grafts embedded deep within the midbrain parenchyma project through the neuropil directly to the overlying superior colliculus, as long as the retina is within about 1 mm of the tectal surface. The present study shows that, as long as the retina is located outside the superior colliculus, and regardless of whether the axons derive from grafts in subpial or intraparenchymal locations, the earliest projections are oriented towards the superior colliculus. We have also found, however, that axons from retinae transplanted directly onto the superior colliculus can form projections that extend along the subpial margin away form the tectum. There are several major conclusions that may be drawn from these observations. First, the final tectopetal, transplant‐derived projection does not result from the reorganization of an initially random outgrowth but is directed from the start toward an appropriate region of termination. Second, it appears that the interaction of retinal axons with a primary target alters the ability of the growth cone to respond to directional cues along the optic tract. Thus, although adding support to the proposal that optic axons attain the superior colliculus through an interaction involving substrates distributed along the optic tract and diffusible factors originating in the target region, it is increasingly clear that such interactions are likely to be complex and hierachical.

UR - http://www.scopus.com/inward/record.url?scp=0025641906&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025641906&partnerID=8YFLogxK

U2 - 10.1002/neu.480210806

DO - 10.1002/neu.480210806

M3 - Article

C2 - 2177099

AN - SCOPUS:0025641906

VL - 21

SP - 1202

EP - 1218

JO - Developmental Neurobiology

JF - Developmental Neurobiology

SN - 1932-8451

IS - 8

ER -