Biomedical subjects

A Tessler

Publications and source records attributed to A Tessler.

At least 37 records · Page 2Linked to original sources

PubMed1999

Embryonic central nervous system transplants mediate adult dorsal root regeneration into host spinal cord.

OBJECTIVE: The aim of this study was to determine whether embryonic central nervous system transplants assisted cut dorsal root axons of adult rats to regenerate into the spinal cord. METHODS: Rats received transplants of embryonic spinal cord, hippocampus, or neocortex into dorsal quadrant cavities aspirated in the lumbar enlargement. The transected L5 dorsal root stump was secured between the transplant and the spinal cord. Regenerated dorsal roots were subsequently labeled by using immunohistochemical methods to detect calcitonin gene-related peptide. RESULTS: Calcitonin gene-related peptide-immunoreactive axons extended into all host spinal cords examined, but the patterns of regrowth differed in rats that had received embryonic spinal cord and brain transplants. In rats with embryonic spinal cord transplants, regenerated axons traversed the dorsal root/spinal cord interface, entered the spinal cord, and frequently formed plexuses with arborizations in motoneuron pools; some of these axons established synapses on spinal cord neurons. In rats with embryonic brain transplants, regenerated axons were diffusely distributed in the spinal cord but did not form plexuses. Few axons regenerated into the spinal cords of lesion-only animals. The results of quantitative analyses confirmed these findings. CONCLUSION: These findings suggest that transplants of embryonic spinal cord and brain supply cues that enable cut dorsal roots to regenerate into the host spinal cord and that the cues provided by spinal cord transplants favor more extensive growth than do those provided by brain transplants. These cues are likely to depend in part on neurotrophic effects of embryonic central nervous system tissues. Therefore, embryonic central nervous system transplants, especially spinal cord grafts, may contribute to techniques for restoring interrupted spinal reflex arcs.

Animals↗

PubMed1998

Intraspinal grafting of fibroblasts genetically modified by recombinant adenoviruses.

Intracerebral or intraspinal grafting of genetically modified primary fibroblasts has been shown to enhance functional recovery in several models of CNS disease, including spinal cord injury. Most of these studies utilized retrovirus vectors. In this report, we describe in vitro conditions for genetically modifying primary fibroblasts with recombinant adenovirus vectors carrying the lacZ or green fluorescent protein (GFP) genes. As intraspinal allografts in animals immunosuppressed by cyclosporin A, the genetically modified cells survived and expressed the transgenes for at least 2 months. We conclude that recombinant adenovirus vectors are efficient and convenient tools for ex vivo gene therapy in the CNS.

Adenoviridae↗

PubMed1998

Critical interval for rescue of axotomized neurons by transplants.

To determine whether embryonic spinal cord transplants retained the ability to prevent retrograde death of Clarke's nucleus (CN) neurons if supplied after a delay, we hemisected adult rats at the T8 spinal cord segment and placed transplants of fetal tissue into the hemisection cavity immediately or up to 14 days later. Transplants provided in the first 7 days after injury prevented virtually all of the 30% loss of CN neurons at L1 ipsilateral to hemisection that occurs without a transplant. Transplants supplied at 14 days post-hemisection were ineffective. Because prevention of retrograde neuron death is one mechanism by which transplants may contribute to locomotor recovery after spinal cord injury, this window of effectiveness should be considered in the design of clinical trials.

Animals↗

PubMed1998

Neurotrophin-3 prevents death of axotomized Clarke's nucleus neurons in adult rat.

In the present investigation, we studied whether neurotrophin-3 (NT-3) contributes to the rescue of axotomized Clarke's nucleus (CN) neurons in adult rats. A significant (24%) loss of CN neurons occurred at L-1 ipsilateral to T-8 hemisection by 14 days, which reached 31% at 2 months and then stabilized. Axotomized CN neurons had also atrophied by 14 days, but mean cell size did not decrease further. Animals that received gelfoam soaked in nerve growth factor, brain derived neurotrophic factor, or ciliary neurotrophic factor at the lesion site also showed a 30% neuron loss at 2 months, and a 40% reduction in average cell area. Rats receiving NT-3 showed a 15% neuron loss, which was not improved by additional neurotrophins in combination with NT-3. None of the treatments prevented neuron atrophy. Bioassay of the gelfoam showed that NT-3 bioactivity remained at 5 days after surgery but not at 14 days. Additional rats with hemisections that received NT-3 continuously via mini-pump for 2 months showed a 15% neuron loss, the same as with NT-3 given via gelfoam. These results indicate that even limited exposure of axotomized CN neurons to NT-3 produces permanent rescue of 50% of the neurons. The virtually complete rescue that we had previously observed with transplants of fetal central nervous system (CNS) tissues may, therefore, be due at least in part to NT-3, but the exogenous administration of a single neurotrophic factor or a combination of neurotrophic factors is less effective than transplants in producing long-term survival of axotomized CNS neurons.

Animals↗

PubMed1997

Application of recombinant adenovirus for in vivo gene delivery to spinal cord.

One strategy for treating spinal cord injury is to supply damaged neurons with the appropriate neurotrophins either by direct delivery or by transfer of the corresponding genes using viral vectors. Here we report the feasibility of using recombinant adenovirus for in vivo gene transfer in spinal cord. After injection of a recombinant adenovirus carrying a beta-galactosidase (beta-gal) reporter gene into the mid-thoracic spinal cord of adult rats, transgene expression occurred not only in several types of cells around the injection site but also in neurons whose axons project to this region from rostral or caudal to the injection site. Among labeled neurons were those of the red nucleus, the vestibular nuclei, reticular formation, locus coeruleus, and Clarke's nucleus. A non-specific immune reaction, which could be blocked by immunosuppression with Cyclosporin A, reduced the number of transduced cells surviving at the injection site by 1 month. In neurons away from the injection site, where the immune response was minimal, transgene expression lasted for at least 2 months. These results support the idea that recombinant adenovirus can be used in the spinal cord for in vivo delivery of therapeutic genes important for supporting neuron survival and axon regeneration.

Adenoviridae↗

PubMed1997

Fetal transplants alter the development of function after spinal cord transection in newborn rats.

Pieces of fetal spinal tissue were transplanted into the site of complete midthoracic spinal transections in neonatal rat pups (transplant rats). The development of locomotion in these animals was compared with that of unoperated control rats and rats that received spinal transections alone (spinal rats). Reflex, treadmill and overground locomotion, staircase descent, and horizontal ladder crossing for a water reward were tested in control, spinal, and transplant rats from 3 weeks to adulthood. All tests were readily performed by control animals. Most spinal rats were unable to make many linked weight-supported steps on these tasks. Transplant rats were variable in their locomotor capabilities, but a subset of rats were able to demonstrate coordinated and adaptable locomotion on these tasks. Some transplant rats performed better on more challenging tasks, suggesting that motor strategies for these tasks used different information, perhaps from descending systems. Transplanted tissue survived, and in most cases there was immunocytochemical staining of serotonergic fibers passing into and caudal to the transplant, supporting the conclusion that descending systems grew through the transplanted tissue. Integration with the host tissue was often poor, suggesting that nonspecific or trophic effects of the transplant might also contribute to the development of locomotor function. Therefore several mechanisms may contribute to the repair of injured spinal cord provided by transplants that permit the development of useful locomotion.

Aging↗

PubMed1997

Fetal spinal cord transplants rescue some axotomized rubrospinal neurons from retrograde cell death in adult rats.

Intraspinal transplants of fetal spinal cord may contribute to recovery after spinal cord injury by keeping axotomized neurons alive. In this study we examined whether transplants rescued axotomized red nucleus (RN) neurons from retrograde cell death in adult rats. RN neurons were labeled by retrograde transport of Fluorogold (FG); 1 week later right-sided RN neurons were axotomized by left-sided hemisection at C3-4 vertebral level, and Embryonic Day 14 spinal cord or gelfoam was introduced into the cavity. Additional rats received hemisection and a transplant of fetal spinal cord or gelfoam without FG injection. At 2 and 4 months, the number of neurons in the magnocellular portion of the RN contralateral to the hemisection decreased 35-40% in rats that received gelfoam; mean soma area of surviving neurons decreased 40%. RN cell loss was reduced to 20% in rats that received fetal spinal cord transplants, but the decrease in mean soma area was unchanged. Transplants therefore rescued about half of the axotomized RN neurons that otherwise would have died but did not prevent perikaryal atrophy. Anterograde transport of WGA-HRP injected into RN 2 months after transplantation showed that rubrospinal axons reached the site of injury but rarely entered transplants; FG injections caudal to transplants showed that axons of transplant neurons extended at least two segments into host spinal cord. Fetal spinal cord transplants may therefore contribute to locomotor recovery in adults with spinal cord injuries both by preventing retrograde cell death and by establishing novel circuits across the site of injury.

Animals↗

PubMed1997

Embryonic spinal cord transplants enhance locomotor performance in spinalized newborn rats.

The results of the present experiments demonstrate that fetal spinal cord transplants placed into the site of a complete transection in newborn rats permit the development of complex patterns of locomotion. These patterns differ in some respects from normal, but include weight support, appropriate postural adjustment, and coordination between forelimbs and hindlimbs. 5-HT agonists administered to transplanted rats can further modify these motor patterns in ways that may prove able to enhance locomotion. When placed into lesion cavities in adult spinal cord, cells genetically modified to express neurotrophins can survive, differentiate, and mimic at least one consequence of fetal transplants, rescue of axotomized neurons from retrograde cell death.

Animals↗

PubMed1997

Neurological assessment in spinal cord injury.

Precise and reliable neurologic assessment is a necessary tool for determining the extent and pattern of recovery after SCI. Recently agreed upon international standards establish a uniform neurologic classification to measure clinical outcomes. They are currently in use in three multicenter studies in more than 40 SCI centers in the United States. The Model System SCI centers report the use of these measures, such as impairment grades and neurologic levels, in almost 15,000 cases over the past 20 years and, more recently, motor scores in 3,500 patients. The NASCIS II multicenter trial on methylprednisolone used motor and sensory scores as endpoints in close to 500 patients, but have incorporated the international standards, which include a disability measure, in NASCIS III. The study of ganglioside effectiveness also is using these measures in many patients. In more focused studies, neurologic assessment soon after injury can predict walking in motor complete injuries based on pin prick sensation, and in motor incomplete injuries based on impairment grade and age. Eventual upper extremity function can be estimated based on the motor examination within 72 hours of injury. Both the motor score and motor level are more reliable in predicting upper extremity function than the single sensory level. This presumably reflects the greater importance of motor recovery on functional outcome. The proximal muscles of the lower extremities caudal to the lesion site recover before distal muscles, and this may be mediated by axons descending in the ventral tracts, which control primarily proximal rather than distal muscles. These axons may be preferentially spared and/or have greater capacity to compensate than those present in the lateral columns. In conclusion, standard neurologic assessment in SCI is extremely valuable in monitoring recovery in order to prognosticate functional outcome, evaluate effectiveness of drug interventions, and provide valuable clues to possible underlying mechanisms of recovery. The elucidation of these mechanisms will aid in the refinement of current treatments and development of new strategies to enhance neurologic recovery and functional outcome.

Humans↗

PubMed1996

Regenerated dorsal root fibers form functional synapses in embryonic spinal cord transplants.

1. The aim of the present study was to determine whether synapses formed by dorsal root afferents that regenerate into intraspinal transplants of fetal spinal cord are functional. Severed L4 or L5 dorsal root stumps were placed at the bottom of dorsal quadrant cavities made in the lumbar spinal cords of adult rats and juxtaposed to embryonic day 14 spinal cord transplants. 2. In animals examined 5-10 weeks later, we recorded extracellularly in transplants from 43 units that fired in response to electrical stimulation of the implanted dorsal root. Latency fluctuations of extracellular firing that increase with stimulus and failure to follow high-frequency and posttetanic potentiation of extracellular firing stimulation suggest that synapses with conventional properties are formed between regenerating afferents and transplant neurons. Limited intracellular recordings confirmed the existence of excitatory postsynaptic potentials in transplant neurons after dorsal root stimulation. 3. In 16 units, extracellular firing occurred in response to single shock stimulation. The remainder of the units required two or more dorsal root shocks to evoke firing; some of these connections also may be monosynaptic. 4. Under the assumption that single shock firing was most likely the result of monosynaptic connections between transplant neurons and regenerated dorsal root fibers, we estimated the conduction velocities of regenerated fibers. These estimates suggest that fibers with conduction velocities in the C, A delta, and A alpha/beta ranges regenerate into transplants of embryonic spinal cord. 5. The results demonstrate that regenerated dorsal root axons establish functional synaptic connections with transplant neurons. The implications for using fetal transplants to help rebuild spinal reflex circuits after spinal cord injury are considered.

Action Potentials↗

PubMed1995

Distribution of Big tau in the central nervous system of the adult and developing rat.

The diversity of neuronal morphology and function is correlated with specific expression of various microtubule associated proteins (MAPs). One of the major neuronal MAPs, tau, has multiple isoforms formed as a result of alternative splicing and phosphorylation that are differentially expressed during development. Big tau is a high molecular weight isoform that contains an additional large exon (4a) and is expressed primarily by neurons in the peripheral nervous system (PNS). We cloned the complete 4a exon in an expression vector, isolated the recombinant protein and produced antibodies specific to Big tau that were used to localize Big tau in the developing spinal cord and in the adult central nervous system (CNS). In developing spinal cord, Big tau is first expressed in the central projections of the dorsal root ganglia neurons and in motor neurons at embryonic day 18 and postnatal day 2, respectively. In the adult rat CNS, almost all neurons that extend processes into the PNS express Big tau, including all cranial nerve motor nuclei and central processes of most sensory ganglia; of these ganglia, only the bipolar neurons of the olfactory, vestibular and spiral ganglia did not express Big tau. Retinal ganglion cells are the only CNS neurons, whose processes remain entirely within the CNS, that express high levels of Big tau. The limited and specific distribution of Big tau is consistent with a role in stabilizing microtubules in axons that are subjected to great shear forces.

Animals↗

PubMed1995

Development of locomotor behavior in the spinal kitten.

This study was undertaken to determine the locomotor capability of kittens whose spinal cords were transected at birth. The postnatal development of reflex and goal-directed locomotion was examined during the first 5 postnatal months in kittens that received low thoracic spinal cord transections as newborns. Some spinal kittens developed aberrant quadrupedal forms of locomotion. The onset of quadrupedal locomotion, however, was delayed by 2-3 months compared to the normal kitten (42) and deteriorated by 5 months of age. Qualitative and quantitative analyses demonstrated that the quadrupedal locomotion was abnormal. Although some step cycles were characterized by full weight support, the typical hindlimb step cycle of the best performing cat showed inadequate weight support and balance. No spinal cat was able to coordinate the hindlimbs with the forelimbs during overground locomotion on a runaway or during quadrupedal locomotion on a treadmill. Neuroanatomical tracing with WGA-HRP and immunocytochemical techniques showed no axonal regeneration or growth into or across the lesion sites. The aberrant form of quadrupedal locomotion developed without descending input to the caudal spinal cord. The variability in performance among animals suggested that compensatory strategies were important factors in the spinal kitten's achievement of quadrupedal locomotion. Hindlimb weight-supported stepping during quadrupedal locomotion in some animals underscored the capacity of the isolated caudal spinal cord to generate both rhythmical stepping movements and weight support. The maintenance of developmentally immature, but functional, hindlimb postures suggested that the development of the isolated caudal spinal cord was arrested in the absence of descending input.

Age Factors↗

PubMed1995

Transplants enhance locomotion in neonatal kittens whose spinal cords are transected: a behavioral and anatomical study.

We have studied the locomotor development of kittens that received complete low thoracic spinal cord transections and embryonic spinal cord transplants as newborns. Embryonic spinal cord (E21-E26) transplanted into the site of a transection integrated well with the host spinal cord and promoted the development of overground locomotion. Spinalized kittens with transplants were first distinguished from spinalized kittens during the 2nd and 3rd postnatal weeks when kittens with transplants positioned their hindlimbs underneath their bodies which promoted support of the hindquarters. By postnatal Week 6, kittens with transplants exhibited overground locomotion characterized by full weight support and moderate balance control. By 20 weeks of age, as many as 96% of the step cycles showed full weight support and as few as 2% of the step cycles were interrupted by a fall. Most kittens also showed coordination between the forelimbs and the hindlimbs. They differed from normal in the precocious onset of reflex stepping and in the less precise interlimb coordination and more precarious balance during overground locomotion. The overground locomotor performance of kittens with transplants greatly exceeded that of spinal kittens without transplants since few spinalized kittens showed any full-weight-supported step cycles and none showed coordination between the forelimbs and the hindlimbs. In the absence of a transplant, no fibers could grow across the lesion site. In the presence of a transplant, fibers grew across the lesion site and established anatomical connectivity with the host. Host segmental systems identified by the presence of calcitonin gene-related peptide- and substance P-immunoreactive fibers were found throughout the transplants. Descending host systems of supraspinal origin were identified by serotonin- and dopamine beta-hydroxylase-immunoreactive fibers throughout the transplants. The growth of supraspinal axons into the transplant, and in one case into the caudal host spinal cord, provided a possible anatomical basis for the development of coordinated overground locomotion.

Age Factors↗

PubMed1995

The expression and distribution of tau proteins and messenger RNA in rat dorsal root ganglion neurons during development and regeneration.

Microtubule-associated proteins contribute to the balance between stability and plasticity of the neuronal cytoskeleton by modulating assembly and disassembly of microtubules. The tau microtubule-associated proteins exist in several isoforms which are developmentally regulated and differentially distributed. Our objective was to characterize the distribution of tau isoforms in developing and mature dorsal root ganglia neurons and during axonal regeneration following sciatic nerve axotomy. Immunocytochemical analysis was carried out using antibodies that recognize all tau isoforms and a novel antibody that specifically recognizes the high molecular weight isoform. The expression of tau is highly regulated during development. At E14, all dorsal root ganglion neurons express only the low molecular weight tau isoforms. These isoforms are still present in all dorsal root ganglion neurons in neonates, whereas high molecular weight tau isoforms are expressed in a subset of dorsal root ganglion neurons. The switch from low to exclusively high molecular weight tau expression begins at E18 and is completed during the first postnatal week. In the adult, high molecular weight tau is restricted to small- and medium-sized dorsal root ganglion neurons; its distribution largely coincides with the population of substance P and calcitonin gene related peptide peptidergic neurons. This differential distribution was observed in the cell body, dorsal roots and sciatic nerve axons. In contrast to the protein, however, the distribution of high molecular weight tau messenger RNA is not restricted; all dorsal root ganglion neurons express similar tau messenger RNA levels. The discrepancy between the distribution of protein and messenger RNA suggests control at the post-transcriptional or translational levels. Sciatic nerve axotomy which is followed by axonal regeneration did not alter the differential distribution of high molecular weight tau immunostaining. We conclude that the distribution and expression of tau isoforms during axonal regeneration in adult does not recapitulate the developmental pattern.

Aging↗

PubMed1994

Grafts of fetal central nervous system tissue rescue axotomized Clarke's nucleus neurons in adult and neonatal operates.

Many conditions are thought to contribute to neuron death after axotomy, including immaturity of the cell at the time of injury, inability to reestablish or maintain target contact, and dependence on trophic factors produced by targets. Exogenous application of neurotrophic factors and transplants of peripheral nerve and embryonic central nervous system (CNS) tissue temporarily rescue axotomized CNS neurons, but permanent rescue may require transplants that are normal targets of the injured neurons. We examined the requirements for survival of axotomized Clarke's nucleus (CN) neurons. Two months after hemisection of the spinal cord at the T8 segment, there was an ipsilateral 30% loss of neurons at the L1 segment in adult operates and a 40% loss in neonates. Transplants of embryonic spinal cord, cerebellum, and neocortex inserted into the T8 segment at the time of hemisection prevented virtually all of the cell death in both adults and neonates, but transplants of embryonic striatum were ineffective. None of the grafts prevented the somal atrophy of CN neurons caused by axotomy. Retrograde transport of fluoro-gold from the cerebellum demonstrated that 33% of all CN neurons at L1 project to the cerebellum, 50% of these died following a T8 hemisection, but all these projection neurons were rescued by a transplant of embryonic spinal cord. These results suggest that the rescue of axotomized CN neurons is relatively specific for the normal target areas of these neurons, but this specificity is not absolute and may depend on the distribution and synthesis of particular neurotrophic agents.

Aging↗

PubMed1993

Restoration of substance P and calcitonin gene-related peptide in dorsal root ganglia and dorsal horn after neonatal sciatic nerve lesion.

Dorsal root ganglion (DRG) neurons decrease their substance P (SP) synthesis after peripheral nerve lesions. Levels in the dorsal horn also decline but return to normal if regeneration is successful. In adults, when regeneration is prevented, recovery of SP in the dorsal horn is slow and incomplete, whereas in newborns, recovery is rapid and complete even though retrograde cell death of DRG neurons is greater than in adults. We have examined the mechanisms that might account for the rapid and complete recovery of SP and calcitonin-gene related peptide (CGRP) in the dorsal horn after peripheral nerve injury in newborns. Peptides were compared in the L4 and L5 DRG and spinal cord segments of normal rats and in rats surviving 6 days to 4 months after sciatic nerve section/ligation within 24 hours of birth. Sciatic nerve section/ligation produced 50% neuron death in L4 and L5 DRGs, but immunocytochemical methods showed that both SP-immunoreactivity (-IR) and CGRP-IR recovered completely in dorsal horn. Radioimmunoassay confirmed that recovery of SP was not an artefact due to shrinkage. beta-Preprotachykinin (PPT)-mRNA hybridization and SP-IR were observed mostly in small neurons; alpha-CGRP-mRNA-hybridized and CGRP-IR neurons were more heterogeneous. The percentage of DRG neurons that contained SP (approximately 25%) or CGRP (approximately 50%) was the same in normal newborn and adult rats. Neither selective cell survival nor change in neuron phenotype was likely to contribute to the recovery seen in the dorsal horn, and DRG neurons ipsilateral to the lesion exhibited the same level of hybridized beta-PPT-mRNA and alpha-CGRP-mRNA as intact DRG neurons. Because neither the constitutive level of expression of the genes nor peptide levels increased above those observed in intact DRG neurons, these mechanisms were also not responsible. Axotomized DRG neurons, however, contributed to recovery. Recovery was also due to sprouting by neurons in intact DRGs rostral and caudal to L4 and L5.

Animals↗

PubMed1993

Time course of dorsal root axon regeneration into transplants of fetal spinal cord: an electron microscopic study.

Intraspinal transplants of fetal CNS tissue permit or enhance the regeneration of cut central axons of adult dorsal root ganglion (DRG) neurons. Some of these regenerated axons establish synapses with transplant neurons. The aims of the present study were to determine when regenerated DRG axons begin to form synapses with transplanted embryonic spinal cord neurons and whether these synapses are permanent. We also examined the development of transplant neuropil in areas innervated by the regenerated axons. Whole pieces of Embryonic Day 14 spinal cord were introduced into hemisection cavities made at the level of the lumbar enlargement, and the cut L4 or L5 dorsal root was juxtaposed to the transplant. Regenerated DRG axons immunoreactive for calcitonin gene-related peptide (CGRP) were labeled by immunohistochemical methods and examined by electron microscopy from 1 week to 1 year after surgery. CGRP-immunoreactive axon terminals made synaptic contacts with dendrites and perikarya of transplant neurons by 1 week after axotomy. The morphology of the synapses was immature. Large growth cone-like structures were also present at 1 week but not at 2 weeks or later. At 2 weeks, regenerated unmyelinated axons formed terminals similar to those found in animals surviving for 48 weeks. Axoaxonic synapses in which the pre- and postsynaptic elements were immunolabeled for CGRP and regenerated CGRP-labeled myelinated axons were observed at 4 weeks and later. The area of distribution of CGRP staining increased until 12 weeks and the synaptic density of regenerated CGRP-labeled terminals increased for 24 weeks. The results indicate that the synaptic terminals of regenerated primary afferent axons are permanently retained within fetal spinal cord transplants. Transplants may therefore contribute to the permanent restoration of interrupted neural circuits.

Animals↗

PubMed1993

Regeneration of adult dorsal root axons into transplants of dorsal or ventral half of foetal spinal cord.

Several dorsal root axons regenerate into the transplants of foetal spinal cord (FSC) and form synapses there. It is unknown whether the growth is specific to transplants of dorsal half FSC, a normal target of most dorsal root axons, or whether it is due to properties shared by transplants of ventral half FSC. We used calcitonin gene-related peptide immunohistochemistry to label subsets of regenerated host dorsal root axons, and morphometric analysis to compared neuronal populations within both transplants. Adult Sprague-Dawley rats received intraspinal grafts of dorsal or ventral half FSC (E14), and the L4 or L5 dorsal root was cut and juxtaposed to the grafts. Three months later sagittal sections were prepared for immunohistochemistry and Nissl-Myelin stain. Histograms of the perikaryal area showed that the transplants of dorsal half FSC consisted of small neurons predominantly, whereas transplants of ventral half FSC consisted of neurons of variable sizes. Dorsal root axons regenerated into both transplants, but growth into dorsal half FSC was more robust. These results indicate that both transplants provide an environment that supports dorsal root regeneration, but that the environment provided by dorsal half FSC is more favorable. Transplants of dorsal half FSC may offer advantages for the long-term goal of repairing of damaged spinal cord circuits.

Animals↗