- Email: [email protected]
Astrocytes colonize dorsal root ganglia transplanted into rat brain
Brain Research Bulktin,
0361.9230/91
Vol. 27, PP. 169-173. 0 Pergamon Press plc, 1991. Printed in the U.S.A.
$3.00 + .OO
Astrocytes Colonize Dorsal Root Ganglia Transplanted Into Rat Brain D. DAHL,
H. MANSOUR
AND A. BIGNAMI’
Department of Pathology, Harvard Medical School and Research and Development Service West Roxbury VA Medical Center, Boston, MA 02132 Received 4 April 199 1 DAHL, D., H. MANSOUR AND A. BIGNAMI. Astrocytes colonize dorsal root ganglia transplanted into rat brain. BRAIN RES BULL 27(2) 169-173, 1991 .-Fragments of dorsal root ganglia (DRG) were grafted into rat brain and examined one month later. The autografts were similar to their normal counterparts when stained with toluidine blue or by indirect immunofluorescence with laminin and neurofilament antibodies. However, a major difference was observed with antibodies to the glial tibrillary acidic protein (GFAP). Normal DRG were GFAP-negative while the autografts were intensely and diffusely stained. The GFAP antibodies used in this study did not decorate Schwann cells or satellite cells in peripheral nerve and DRG, and thus appeared to recognize the “central” form of GFAP (17). Thus reactive astrocytes appear to be capable of migration into grafted nervous tissues without producing apparent neuronal damage. Astrocyte
migration
GFAP
Neurofilament
slightly above the corpus callosum. DRG were implanted either close to the surface or deep into the cerebral hemisphere. One month after operation, rats were asphyxiated with CO,. The brain was removed and the operated cerebral hemisphere was placed on a tissue holder with embedding medium and frozen on dry ice. The hemisphere was cut serially with a cryostat and air-dried sections (approximately 10 p,m thick) were fixed in acetone for 10 min at 4°C. One section in ten was stained with toluidine blue. Sections containing the graft were stained with monoclonal antibodies of mouse origin followed by polyclonal antibodies raised in rabbits. The following antibodies were used: neurofilament monoclonal 558 (10); neurofilament polyclonal R39 (6); GFAP monoclonal A,D, (8); GFAP polyclonal Kl (5); laminin polyclonal (GIBCO Laboratories, Grand Island, NY). GFAP monoclonal A2D, failed to stain peripheral glia, including satellite glia in dorsal root ganglia and Schwann cells in peripheral nerve undergoing Wallerian degeneration (9).
THE astrocytic reaction that follows neuronal damage in pathological conditions not associated with the disruption of the blood-brain barrier is confined strictly to the site of injury. As a specific example, isomorphic gliosis in Wallerian degeneration does not extend beyond the transected white matter tracts. Conversely, in stab wounds that disrupt the blood-brain barrier, the astrocytic response extends well beyond the site of trauma. This is generally believed to be due to the activation of resident astrocytes by blood-derived growth factors. Such growth factors are then able to enter and diffuse into brain tissue as a result of vascular damage [see (20) for review]. Here we report experiments aimed at finding out whether astrocytic migration could play a role in the phenomenon. For this purpose, dorsal root ganglia (DRG) were implanted into the brain, with the assumption that the presence of astrocytes within DRG would provide evidence for their migratory capabilities. Astrocytes are only found in the central nervous system in normal conditions. Another purpose of the work was to find out whether reactive astrocytes were associated with neuronal damage, if in fact they were able to migrate into DRG.
RESULTS
In intraparenchymal implants, the brain graft interface was identified easily with laminin antibodies. As their normal counterparts, grafted DRGs were stained intensely, while in the surrounding brain laminin immunoreactivity was confined to blood vessels (Fig. 1A). Conversely, the GFAP antibodies did not allow the identification of the brain-graft interface. The severe gliosis surrounding the implant extended without interruption of continuity inside the DRG (Fig. 1B). The transition from normal astrocytes in white matter to the severe gliosis involving DRG and surrounding brain tissue is illustrated in Fig. 2. The main distinctive feature between gliosed brain and ganglion was
METHOD
Adult female Sprague-Dawley rats weighing 250-300 g were purchased from Taconic Farms (Germantown, NY). All surgical procedures were carried out under general anesthesia (pentobarbital IP 15 mg/kg). Following craniectomy and a wide laminectomy at the lumbar level, a dorsal root ganglion was exposed by opening the intervertebral foramen under a dissecting microscope. The exposed ganglion was removed and fragments were transplanted into the left cerebral hemisphere of the same animal ‘Requests for reprints should be addressed West Roxbury, MA 02132.
to A. Bignami,
M.D.,
Research
169
and Development
(151). HVA Medical Center,
1490 VFW Parkway,
I70
DAHL. iMANSC)lJK X’JL) BIGNAMI
FIG. I. Dorsal root ganglion
grafted in rat cerebral hemisphere one month after tmplantation. The section is double-stained with lammm polyclonal antibodies of rabbit origin (A, fluorescein optics) and with GFAP monoclonal antibody AaD, of mouse origin (B, rhodamme optics]. The graft brain boundary is easily detectable with antilaminin, but not with GFAP antibodies. In brain tissue, laminin immunoreactivity IX confined to blood vessels. while both the implant and surrounding brain tissue stain intensely with anti-GFAP. y 160
the presence of empty spaces in the latter probably corresponding to DRG neurons. In intraventricular grafts, gliosis was less pronounced and appeared to be confined to the zone of attachment to the ventricular surface (Fig. 3). Regardless of their location (intraparenchymal or intraventricular), the ganglia appeared well preserved in sections stained with toluidine blue and with neurofilament antibodies (Fig. 4). The gliotic brain tissue surrounding the grafts was devoid of axons consistently. thus indicating that axonal sprouting had not occurred beyond the implants.
IXSCUSSION
The question of astrocyte migration into host tissues has been addressed by several authors (11, 13-15, 16, 18. 19, 21, 28). Most studies have shown that transplanted astrocytes are capable of migrating for several millimeters in the surrounding brain. Migration of as much as 50 mm has been reported by Goldberg and Bernstein (13-1.5). Although the findings are relevant to the question of glial migration in development, they still do not address the issue as to whether reactive astrocytes are stationary or
ASTROCYTE
MIGRATION
171
INTO DRG GRAFTS
FIG. 2. Dorsal root ganglion grafted in rat cerebral hemisphere one month after operation.
Indirect immtmofluorescence with GFAP monoclonal antibody AaD,. Note the transition from stellate astrocytes in normal white matter to a mesh of fibers becoming progressively denser in the tissues surrounding the graft. In the graft itself, the mesh is looser probably due to the presence of nonstained DRG neurons interspersed among the glial bundles. X 160
mobile cells. In most of these experiments, glial cells migrating into host brain originated from either fetal or newborn brain explants. More relevant to the topic of the present paper are reports of astrocyte migration in peripheral nerves (3, 4, 12, 25) and autonomic ganglia (22, 23, 27) grafted to mature brain. In peripheral nerve grafts astrocyte migration was an extremely limited phenomenon compared to what we observed in DRG implants. Another important point is that the glial fibrlllary scar at the brain-graft interface did not prevent axons from entering the denervated peripheral nerve implant (3). Conversely, the gliotic capsule surrounding the DRG graft was completely devoid of axons, thus indicating that axons did not enter or leave the graft. Astrocytes were more prominent in autono~c ganglia and, in accordance with our observations of DRG grafts, the extent of astrocyte migration was more pronounced in intraparenchyma1 as compared to intraventricular grafts (23). Our study is the first to confirm the migration of astrocytes into peripheral nerve tissue grafted into the brain with monoclonal antibodies reacting with the “central” form of GFAP. It is generally accepted that GFAP is not confined to astrocytes in
CNS, but also resides in peripheral glia, i.e., Schwann cells surrounding nonmyelinated axons, satellite cells in sensory ganglia and many enteric glia (7, 17, 26). Furthermore, as in astrocytes, GFAP immunoreactivity is enhanced in peripheral glia as a result of injury (7,26). Thus even if peripheral ganglia stain little with the polyclonal GFAP antibodies, the possibility of increased immuno~activity as a result of ~anspl~tation could still be considered. Finally, even if our findings conclusively demonstrate that reactive astrocytes are capable of migration, it still remains to be seen whether like young astrocytes, they are able to do so in mature CNS tissues. Two minor components of CNS myelin have been reported to inhibit axonal growth (24), and it is possible that they aIso inhibit astrocyte migmtion. Fu~he~o~, the extracellular matrices of PNS and CNS are different. In brain, like in cartilage, a hyaluronate-protein complex may not provide a suitable terrain for cell migration (1,2). ACKNOWLEDGEMENTS This work was supported ans Adminis~ation.
by NIH grant NS 13034 and by the Veter-
REFERENCES 1. Asher, R.; Perides, G.; Vanderhaeghen, J.-J.; Bignami, A. The extracellular matrix of central nervous system white matter: demon-
stration of an hyaluronate-protein 41@-421; 1991.
complex.
J. Neurosci.
Res. 28:
172
DAHL.
:MANSOUK
liND Hl(~NAMI
FIG. 3. lntraventricular dorsal root ganglion grafted m rat cerebral hemisphere one month after operation. ‘The \ectlon is double-labeled with laminin polyclonal antibodies of rabbit origin (A. fluorescein optics) and with GFAP monoclonal antibody AzDJ of mouse origin (B, rhodamme optics). As evidenced by GFAP immunoreactivity, astrocytic invasion proceeding from the site of attachment on the ventricular wall is le\s e~terlsive when compared to grafts surrounded by brain tissue (see. Fig. 1I. hv. hlood vessel. Y 160
2. Bignami, A.; Lane, W. S.; Andrews, D.; Dahl, D. Structural similarity of hyaluronate binding proteins in brain and cartilage. Brain Res. Bull. 22:67-70; 1989. 3. Chi, N. H.; Dahl, D. Autologous peripheral nerve grafting into murine brain as a model for studies of regeneration in the central nervous system. Exp. Neurol. 79:245-264; 1983. 4. Chi, N. H.; Bignami, A.: Bich, N. T.; Dahl, D. Autologous sciatic nerve grafts to the rat spinal cord: Immunofluorescence studies with neurofilament and gliofilament (GFA) antisera. Exp. Neurol. 68: 568-580; 1980. 5. Dahl, D.; Bignami, A. Immunogenic properties of the glial fibrillary acidic protein. Brain Res. 116:150-157; 1976. 6. Dabl, D.; Bignami, A. Preparation of antisera to neurofilament protein from chicken brain and human sciatic nerve. J. Comp. Neurol. 1761645-657; 1977. 7. Dahl, D.; Chi, N. H.; Miles, L. E.; Nguyen, B. T.; Bignami, A. Cilia1 fibrillary acidic (GFA) protein in Schwann cells: fact or artifact? J. Histochem. Cytochem. 30:912-918; 1982. 8. Dahl. D.; Grossi, M.; Bignami, A. Masking of epitopes in tissue sections. A study of glial fibrillary acidic (GFA) protein with antisera and monoclonal antibodies. Histochemistry 8 I :525-53 1; 1984. markers in 9. Dahl, D.; Bjijrklund, H.; Bignami, A. Immunological astrocytes. In: Fedoroff, S.; Vemadakis, A., eds. Astrocytes. New York: Academic Press; 1986;1-25. IO. Dahl, D.; Gardner, E. E.; Crosby, C. J. Axonal maturation in development. I. Characterization of monoclonal antibodies reacting with axon-specific neurofilament epitopes. Int. J. Dev. Neurosci. 5:17-27; 1987. II. Emmett, C. J.; Lawrence, J. M.; Seeley, P. J. Visualization of migration of transplanted astrocytes using polystyrene microspheres.
Brain Res. 447:223-233; 1988. 12. Fishman. P. S.; Nilaver, G.; Kelly, J. P. Astroghoais limits the integration of peripheral nerve grafts into the spinal cord. Brain Res, 277:175-180; 1983. 13. Goldberg, W. J.; Bernstein. J. J. Transplant-derived astrocytes migrate into host lumbar and cervical spinal cord after implantation of El4 fetal cerebral cortex into adult thoracic spinal cord. J. Neurosci. Res. 17:391-103; 1987. 14. Goldberg, W. J.: Bernstein, J. J. Migration of cultured fetal spinal cord astrocytes into adult host cervical cord and medulla following transplantation into thoracic spinal cord. J. Neurosci. Res. 19:3& 42; 1988. 15. Goldberg, W. J.; Bernstein, J. J. Fetal cortical astrocytes migrate from control homografts throughout the host brain and over the glia limitans. J. Neurosci. Res. 20:38-45; 1988. 16. Jacque, C. M.; Suard, I. M.; Collins, V. P.; Raoul, M. M. Interspecies identification of astrocytes after intracerebral transplantation. Dev. Neurosci. 8:142-149; 1986. 17. Jessen, K. R.: Thorpe, R.; Mirsky, R. Molecular identity, distribution and heterogeneity of glial fibrillary acidic protein; an immunoblotting and immunohistochemical study of Schwann cells, satellite cells, enteric glia and astrocytes. J. Neurocytol. I3:187-200; 1984. study of neu18. Lindsay, R. M.; Raisman, G. An autoradiographic ronal development, vascularization and glial cell migration from hippocampal transplants labeled in intermediate explant culture. Neuroscience 12:513-530; 1984. 19. Lund, R. D.; Houston, M. B.; Lagenaur, C. F.; Kunz. H. W.; Gill, T. J. III. Cellular events associated with induced rejection of neural xenografts placed into neonatal rat brains. Transplant. Proc. 21: 3174-3175: 1989.
ASTROCYTE
MIGRATION
173
INTO DRG GRAFTS
FIG. 4. Dorsal root ganglion (DRG) grafted in rat cerebral hemisphere one month after operation. Indirect immunofluorescence with neurofilament antibody monoclonal JJ8. Note that DRG axons do not extend into the surrounding brain tissue. x 160. Inset. DRG neurons at higher magnification. x 400.
20. Malhotra, S. K.; Shnitka, T. K.; Elbrink, J. Reactive astrocytes-a review. Cytobios 61:133-160; 1990. 21. Raisman, G.; Lawrence, J. M.; Zhou, C. F.; Lindsay, R. M. Some neuronal, glial and vascular interactions which occur when developing hippocampal primordia are incorporated into adult host hippocampi. In: Bjorklund, A.; Swanson, L. W.; eds. Neural grafting in the mammalian CNS. Amsterdam: Elsevier; 1985:125-149. 22. Rosenstein, J. M.; Brightman, M. W. Anomalous migration of central nervous tissue to transplanted autonomic ganglia. J. Neurocytol. 10:387-409; 1981. 23. Rosenstein, J. M.; Krum, J. M.; Trapp, B. D. The astroglial response to autonomic tissue grafts. Brain Res. 476: 110-l 19; 1989. 24. Schwab, M. E. Myelin-associated inhibitors of neurite growth and regeneration in the CNS. Trends Neurosci. 13:452456; 1990.
25. Weinberg, E. L.; Raine, C. S. Reinnervation of peripheral nerve segments implanted into rat central nervous system. Brain Res. 198: l-l 1; 1980. 26. Yen, S.-H; Fields, K. L. Antibodies to neurofilament, glial filament and tibroblast intermediate filament proteins bind to different cell types of the nervous system. J. Cell Biol. 88:115-126; 1981. 27. Zhou, C. F.; Lawrence, J. M.; Morris, R. J.; Raisman, G. Migration of host astrocytes into superior sympathetic ganglia autografted into the septal nuclei or choroid fissure of adult rats. Neuroscience 17:815-827; 1986. 28. Zhou, H. F.; Lee, L. H.-C.; Lund, R. D. Timing and patterns of astrocyte migration from xenogeneic transplants of the cortex and corpus callosum. J. Comp. Neurol. 29:320-330; 1990.
0361.9230/91
Vol. 27, PP. 169-173. 0 Pergamon Press plc, 1991. Printed in the U.S.A.
$3.00 + .OO
Astrocytes Colonize Dorsal Root Ganglia Transplanted Into Rat Brain D. DAHL,
H. MANSOUR
AND A. BIGNAMI’
Department of Pathology, Harvard Medical School and Research and Development Service West Roxbury VA Medical Center, Boston, MA 02132 Received 4 April 199 1 DAHL, D., H. MANSOUR AND A. BIGNAMI. Astrocytes colonize dorsal root ganglia transplanted into rat brain. BRAIN RES BULL 27(2) 169-173, 1991 .-Fragments of dorsal root ganglia (DRG) were grafted into rat brain and examined one month later. The autografts were similar to their normal counterparts when stained with toluidine blue or by indirect immunofluorescence with laminin and neurofilament antibodies. However, a major difference was observed with antibodies to the glial tibrillary acidic protein (GFAP). Normal DRG were GFAP-negative while the autografts were intensely and diffusely stained. The GFAP antibodies used in this study did not decorate Schwann cells or satellite cells in peripheral nerve and DRG, and thus appeared to recognize the “central” form of GFAP (17). Thus reactive astrocytes appear to be capable of migration into grafted nervous tissues without producing apparent neuronal damage. Astrocyte
migration
GFAP
Neurofilament
slightly above the corpus callosum. DRG were implanted either close to the surface or deep into the cerebral hemisphere. One month after operation, rats were asphyxiated with CO,. The brain was removed and the operated cerebral hemisphere was placed on a tissue holder with embedding medium and frozen on dry ice. The hemisphere was cut serially with a cryostat and air-dried sections (approximately 10 p,m thick) were fixed in acetone for 10 min at 4°C. One section in ten was stained with toluidine blue. Sections containing the graft were stained with monoclonal antibodies of mouse origin followed by polyclonal antibodies raised in rabbits. The following antibodies were used: neurofilament monoclonal 558 (10); neurofilament polyclonal R39 (6); GFAP monoclonal A,D, (8); GFAP polyclonal Kl (5); laminin polyclonal (GIBCO Laboratories, Grand Island, NY). GFAP monoclonal A2D, failed to stain peripheral glia, including satellite glia in dorsal root ganglia and Schwann cells in peripheral nerve undergoing Wallerian degeneration (9).
THE astrocytic reaction that follows neuronal damage in pathological conditions not associated with the disruption of the blood-brain barrier is confined strictly to the site of injury. As a specific example, isomorphic gliosis in Wallerian degeneration does not extend beyond the transected white matter tracts. Conversely, in stab wounds that disrupt the blood-brain barrier, the astrocytic response extends well beyond the site of trauma. This is generally believed to be due to the activation of resident astrocytes by blood-derived growth factors. Such growth factors are then able to enter and diffuse into brain tissue as a result of vascular damage [see (20) for review]. Here we report experiments aimed at finding out whether astrocytic migration could play a role in the phenomenon. For this purpose, dorsal root ganglia (DRG) were implanted into the brain, with the assumption that the presence of astrocytes within DRG would provide evidence for their migratory capabilities. Astrocytes are only found in the central nervous system in normal conditions. Another purpose of the work was to find out whether reactive astrocytes were associated with neuronal damage, if in fact they were able to migrate into DRG.
RESULTS
In intraparenchymal implants, the brain graft interface was identified easily with laminin antibodies. As their normal counterparts, grafted DRGs were stained intensely, while in the surrounding brain laminin immunoreactivity was confined to blood vessels (Fig. 1A). Conversely, the GFAP antibodies did not allow the identification of the brain-graft interface. The severe gliosis surrounding the implant extended without interruption of continuity inside the DRG (Fig. 1B). The transition from normal astrocytes in white matter to the severe gliosis involving DRG and surrounding brain tissue is illustrated in Fig. 2. The main distinctive feature between gliosed brain and ganglion was
METHOD
Adult female Sprague-Dawley rats weighing 250-300 g were purchased from Taconic Farms (Germantown, NY). All surgical procedures were carried out under general anesthesia (pentobarbital IP 15 mg/kg). Following craniectomy and a wide laminectomy at the lumbar level, a dorsal root ganglion was exposed by opening the intervertebral foramen under a dissecting microscope. The exposed ganglion was removed and fragments were transplanted into the left cerebral hemisphere of the same animal ‘Requests for reprints should be addressed West Roxbury, MA 02132.
to A. Bignami,
M.D.,
Research
169
and Development
(151). HVA Medical Center,
1490 VFW Parkway,
I70
DAHL. iMANSC)lJK X’JL) BIGNAMI
FIG. I. Dorsal root ganglion
grafted in rat cerebral hemisphere one month after tmplantation. The section is double-stained with lammm polyclonal antibodies of rabbit origin (A, fluorescein optics) and with GFAP monoclonal antibody AaD, of mouse origin (B, rhodamme optics]. The graft brain boundary is easily detectable with antilaminin, but not with GFAP antibodies. In brain tissue, laminin immunoreactivity IX confined to blood vessels. while both the implant and surrounding brain tissue stain intensely with anti-GFAP. y 160
the presence of empty spaces in the latter probably corresponding to DRG neurons. In intraventricular grafts, gliosis was less pronounced and appeared to be confined to the zone of attachment to the ventricular surface (Fig. 3). Regardless of their location (intraparenchymal or intraventricular), the ganglia appeared well preserved in sections stained with toluidine blue and with neurofilament antibodies (Fig. 4). The gliotic brain tissue surrounding the grafts was devoid of axons consistently. thus indicating that axonal sprouting had not occurred beyond the implants.
IXSCUSSION
The question of astrocyte migration into host tissues has been addressed by several authors (11, 13-15, 16, 18. 19, 21, 28). Most studies have shown that transplanted astrocytes are capable of migrating for several millimeters in the surrounding brain. Migration of as much as 50 mm has been reported by Goldberg and Bernstein (13-1.5). Although the findings are relevant to the question of glial migration in development, they still do not address the issue as to whether reactive astrocytes are stationary or
ASTROCYTE
MIGRATION
171
INTO DRG GRAFTS
FIG. 2. Dorsal root ganglion grafted in rat cerebral hemisphere one month after operation.
Indirect immtmofluorescence with GFAP monoclonal antibody AaD,. Note the transition from stellate astrocytes in normal white matter to a mesh of fibers becoming progressively denser in the tissues surrounding the graft. In the graft itself, the mesh is looser probably due to the presence of nonstained DRG neurons interspersed among the glial bundles. X 160
mobile cells. In most of these experiments, glial cells migrating into host brain originated from either fetal or newborn brain explants. More relevant to the topic of the present paper are reports of astrocyte migration in peripheral nerves (3, 4, 12, 25) and autonomic ganglia (22, 23, 27) grafted to mature brain. In peripheral nerve grafts astrocyte migration was an extremely limited phenomenon compared to what we observed in DRG implants. Another important point is that the glial fibrlllary scar at the brain-graft interface did not prevent axons from entering the denervated peripheral nerve implant (3). Conversely, the gliotic capsule surrounding the DRG graft was completely devoid of axons, thus indicating that axons did not enter or leave the graft. Astrocytes were more prominent in autono~c ganglia and, in accordance with our observations of DRG grafts, the extent of astrocyte migration was more pronounced in intraparenchyma1 as compared to intraventricular grafts (23). Our study is the first to confirm the migration of astrocytes into peripheral nerve tissue grafted into the brain with monoclonal antibodies reacting with the “central” form of GFAP. It is generally accepted that GFAP is not confined to astrocytes in
CNS, but also resides in peripheral glia, i.e., Schwann cells surrounding nonmyelinated axons, satellite cells in sensory ganglia and many enteric glia (7, 17, 26). Furthermore, as in astrocytes, GFAP immunoreactivity is enhanced in peripheral glia as a result of injury (7,26). Thus even if peripheral ganglia stain little with the polyclonal GFAP antibodies, the possibility of increased immuno~activity as a result of ~anspl~tation could still be considered. Finally, even if our findings conclusively demonstrate that reactive astrocytes are capable of migration, it still remains to be seen whether like young astrocytes, they are able to do so in mature CNS tissues. Two minor components of CNS myelin have been reported to inhibit axonal growth (24), and it is possible that they aIso inhibit astrocyte migmtion. Fu~he~o~, the extracellular matrices of PNS and CNS are different. In brain, like in cartilage, a hyaluronate-protein complex may not provide a suitable terrain for cell migration (1,2). ACKNOWLEDGEMENTS This work was supported ans Adminis~ation.
by NIH grant NS 13034 and by the Veter-
REFERENCES 1. Asher, R.; Perides, G.; Vanderhaeghen, J.-J.; Bignami, A. The extracellular matrix of central nervous system white matter: demon-
stration of an hyaluronate-protein 41@-421; 1991.
complex.
J. Neurosci.
Res. 28:
172
DAHL.
:MANSOUK
liND Hl(~NAMI
FIG. 3. lntraventricular dorsal root ganglion grafted m rat cerebral hemisphere one month after operation. ‘The \ectlon is double-labeled with laminin polyclonal antibodies of rabbit origin (A. fluorescein optics) and with GFAP monoclonal antibody AzDJ of mouse origin (B, rhodamme optics). As evidenced by GFAP immunoreactivity, astrocytic invasion proceeding from the site of attachment on the ventricular wall is le\s e~terlsive when compared to grafts surrounded by brain tissue (see. Fig. 1I. hv. hlood vessel. Y 160
2. Bignami, A.; Lane, W. S.; Andrews, D.; Dahl, D. Structural similarity of hyaluronate binding proteins in brain and cartilage. Brain Res. Bull. 22:67-70; 1989. 3. Chi, N. H.; Dahl, D. Autologous peripheral nerve grafting into murine brain as a model for studies of regeneration in the central nervous system. Exp. Neurol. 79:245-264; 1983. 4. Chi, N. H.; Bignami, A.: Bich, N. T.; Dahl, D. Autologous sciatic nerve grafts to the rat spinal cord: Immunofluorescence studies with neurofilament and gliofilament (GFA) antisera. Exp. Neurol. 68: 568-580; 1980. 5. Dahl, D.; Bignami, A. Immunogenic properties of the glial fibrillary acidic protein. Brain Res. 116:150-157; 1976. 6. Dabl, D.; Bignami, A. Preparation of antisera to neurofilament protein from chicken brain and human sciatic nerve. J. Comp. Neurol. 1761645-657; 1977. 7. Dahl, D.; Chi, N. H.; Miles, L. E.; Nguyen, B. T.; Bignami, A. Cilia1 fibrillary acidic (GFA) protein in Schwann cells: fact or artifact? J. Histochem. Cytochem. 30:912-918; 1982. 8. Dahl. D.; Grossi, M.; Bignami, A. Masking of epitopes in tissue sections. A study of glial fibrillary acidic (GFA) protein with antisera and monoclonal antibodies. Histochemistry 8 I :525-53 1; 1984. markers in 9. Dahl, D.; Bjijrklund, H.; Bignami, A. Immunological astrocytes. In: Fedoroff, S.; Vemadakis, A., eds. Astrocytes. New York: Academic Press; 1986;1-25. IO. Dahl, D.; Gardner, E. E.; Crosby, C. J. Axonal maturation in development. I. Characterization of monoclonal antibodies reacting with axon-specific neurofilament epitopes. Int. J. Dev. Neurosci. 5:17-27; 1987. II. Emmett, C. J.; Lawrence, J. M.; Seeley, P. J. Visualization of migration of transplanted astrocytes using polystyrene microspheres.
Brain Res. 447:223-233; 1988. 12. Fishman. P. S.; Nilaver, G.; Kelly, J. P. Astroghoais limits the integration of peripheral nerve grafts into the spinal cord. Brain Res, 277:175-180; 1983. 13. Goldberg, W. J.; Bernstein. J. J. Transplant-derived astrocytes migrate into host lumbar and cervical spinal cord after implantation of El4 fetal cerebral cortex into adult thoracic spinal cord. J. Neurosci. Res. 17:391-103; 1987. 14. Goldberg, W. J.: Bernstein, J. J. Migration of cultured fetal spinal cord astrocytes into adult host cervical cord and medulla following transplantation into thoracic spinal cord. J. Neurosci. Res. 19:3& 42; 1988. 15. Goldberg, W. J.; Bernstein, J. J. Fetal cortical astrocytes migrate from control homografts throughout the host brain and over the glia limitans. J. Neurosci. Res. 20:38-45; 1988. 16. Jacque, C. M.; Suard, I. M.; Collins, V. P.; Raoul, M. M. Interspecies identification of astrocytes after intracerebral transplantation. Dev. Neurosci. 8:142-149; 1986. 17. Jessen, K. R.: Thorpe, R.; Mirsky, R. Molecular identity, distribution and heterogeneity of glial fibrillary acidic protein; an immunoblotting and immunohistochemical study of Schwann cells, satellite cells, enteric glia and astrocytes. J. Neurocytol. I3:187-200; 1984. study of neu18. Lindsay, R. M.; Raisman, G. An autoradiographic ronal development, vascularization and glial cell migration from hippocampal transplants labeled in intermediate explant culture. Neuroscience 12:513-530; 1984. 19. Lund, R. D.; Houston, M. B.; Lagenaur, C. F.; Kunz. H. W.; Gill, T. J. III. Cellular events associated with induced rejection of neural xenografts placed into neonatal rat brains. Transplant. Proc. 21: 3174-3175: 1989.
ASTROCYTE
MIGRATION
173
INTO DRG GRAFTS
FIG. 4. Dorsal root ganglion (DRG) grafted in rat cerebral hemisphere one month after operation. Indirect immunofluorescence with neurofilament antibody monoclonal JJ8. Note that DRG axons do not extend into the surrounding brain tissue. x 160. Inset. DRG neurons at higher magnification. x 400.
20. Malhotra, S. K.; Shnitka, T. K.; Elbrink, J. Reactive astrocytes-a review. Cytobios 61:133-160; 1990. 21. Raisman, G.; Lawrence, J. M.; Zhou, C. F.; Lindsay, R. M. Some neuronal, glial and vascular interactions which occur when developing hippocampal primordia are incorporated into adult host hippocampi. In: Bjorklund, A.; Swanson, L. W.; eds. Neural grafting in the mammalian CNS. Amsterdam: Elsevier; 1985:125-149. 22. Rosenstein, J. M.; Brightman, M. W. Anomalous migration of central nervous tissue to transplanted autonomic ganglia. J. Neurocytol. 10:387-409; 1981. 23. Rosenstein, J. M.; Krum, J. M.; Trapp, B. D. The astroglial response to autonomic tissue grafts. Brain Res. 476: 110-l 19; 1989. 24. Schwab, M. E. Myelin-associated inhibitors of neurite growth and regeneration in the CNS. Trends Neurosci. 13:452456; 1990.
25. Weinberg, E. L.; Raine, C. S. Reinnervation of peripheral nerve segments implanted into rat central nervous system. Brain Res. 198: l-l 1; 1980. 26. Yen, S.-H; Fields, K. L. Antibodies to neurofilament, glial filament and tibroblast intermediate filament proteins bind to different cell types of the nervous system. J. Cell Biol. 88:115-126; 1981. 27. Zhou, C. F.; Lawrence, J. M.; Morris, R. J.; Raisman, G. Migration of host astrocytes into superior sympathetic ganglia autografted into the septal nuclei or choroid fissure of adult rats. Neuroscience 17:815-827; 1986. 28. Zhou, H. F.; Lee, L. H.-C.; Lund, R. D. Timing and patterns of astrocyte migration from xenogeneic transplants of the cortex and corpus callosum. J. Comp. Neurol. 29:320-330; 1990.