Unoperated Side Research Articles

Kinetics of facial motoneuron loss following facial nerve transection in severe combined immunodeficient mice.

We have recently shown that cells of the acquired immune system are crucial components of motoneuron survival after injury (Serpe et al. [1999] J. Neurosci. 19:RC7). The goal of the present study was to determine the kinetics of facial motoneuron (FMN) loss in wild-type, scid, and reconstituted scid mice after a right facial nerve axotomy at the stylomastoid foramen. Scid mice showed a significant decrease in FMN survival at all weekly postoperative (wpo) times. One, two, four, and ten wpo, ipsilateral FMN survival in scid mice was 90% +/- 1.8%, 84% +/- 1.3%, 52% +/- 3.7%, and 45% +/- 2.5%, respectively, of the contralateral, unoperated side. In contrast, FMN loss after axotomy in wild-type and reconstituted scid mice was not observed until 4 wpo (86% +/- 2.5% and 83% +/- 3.5%, respectively) relative to the contralateral, unoperated side. However, the levels of FMN in both wild-type and reconstituted scid mice were significantly higher than those in the nonreconstituted scid at 4 wpo. By 10 wpo, FMN survival in both wild-type and reconstituted scid mice had continued to decline significantly (60% +/- 2.1% and 58% +/- 3.1%, respectively) relative to the contralateral, unoperated side but were still significantly higher than that of the nonreconstituted scid at 10 wpo. Several important controls were also added to this study. Because the scid mutation is present in all cells (although it specifically results in a loss of V(D)J recombination mechanisms, we wanted to rule out the actual DNA mutation as causal in FMN loss). To accomplish this, we used the recombinase-activating gene-2 knockout (RAG-2 KO) mouse model, in which the RAG-2 has been disrupted and prevents maturation of T and B cells. As with the scid model, there was a significant loss of FMN at 4 wpo in the RAG-2 KO that could be reversed with whole splenocyte reconstitution. We also compared FMN numbers in nonaxotomized facial nuclei from both scid and RAG-2 KO mice relative to wild-type controls. No differences in normal numbers of FMN were found in either the mutation or the gene knockout model. The ability of T and B lymphocytes to rescue FMN from cell death after peripheral nerve injury supports the hypothesis that cells of the acquired immune system produce neurotrophic factors or neurocytokines to support neuronal survival until target reconnection occurs.

もやもや病に対する間接的血管吻合術におけるfacts and myths-revisit-

I revisit items in an earlier paper of the same title, a review article that appeared in Nerv Syst Child (17: 219-229, 1992) with new conceptual understanding of the disease and its treatment. The items discussed are as follows. A. Is arachnoid incision needed in indirect anastomosis.? B. Does it take several months for an indirect anastomosis to have effects? C. Is surgery indicated for indirect anastomoses in the adult or the aged? D. Are indirect anastomoses less effective and trustworthy than direct operations? E. Does it matter little to discontinue the STA in the operation of moyamoya disease? F. Is surgery indicated for patients who just have occasional TIA attacks? G. Is surgery indicated for patients who just have headaches? H. Is surgery indicated for epileptic-type moyamoya patients? I. Is the operation not indicated for the seriously retarded? J. Are indirect anastomoses effective on the normal or infarcted brain? K. Under what circumstances is indirect anastomosis most effective? L. Should the operation be done bilaterally in one operation? M. Should an indirect operation be as extensive as possible?The answers are as follows. A. No arachnoid incision is needed in indirect anastomosis. B. It takes only weeks for an indirect anastomosis to have effects. C. Indirect anastomoses are indicated for the adult and the aged. D. It has never been proved scientifically that indirect anastomoses are less effective and trustworthy than direct operations. E. Discontinuance of the STA should be avoided if possible during the operation of moyamoya disease. F. Surgery is indicated even for patients who just have occasional TIA attacks. G. Surgery is also indicated for patients who just have headaches. H. Surgery also is indicated for epileptic-type moyamoya patients. I. Surgery is also indicated for the seriously retarded. J. Indirect anastomoses are less effective on the infarcted brain and much less so on the normal brain. K. Indirect anastomosis is most effective on live, misery perfused or hemodynamically-stressed brain. L. If the operation is to be done in two stages, the patient should be cautiously followed because the unoperated side deteriorates very rapidly in some cases. M. There should be an optimal extensiveness of an indirect operation in each case.

The direct effect of intraorbital pressure on orbital growth in the anophthalmic piglet.

Tissue expanders placed within the orbit can have a positive effect on orbital and ipsilateral midfacial growth. To date, there is no precise method for controlling and monitoring expansion to induce normal growth in the developing facial skeleton. The present study was undertaken to determine the optimal physiologic pressure required to stimulate normal orbital growth and to determine whether above-normal growth could be achieved with higher intraorbital pressures. Using a neonatal swine model, an accurate method of monitoring intraorbital pressure, precisely controlling intraorbital expansion, and achieving normal orbital growth was explored. Sixteen male, 3-week-old Yorkshire piglets were randomly divided into three surgical groups. In each group, the left orbit was the experimental side, and the contralateral right orbit served as an untreated control. Group 1 (n = 6) underwent enucleation only. Group 2 (n = 5) underwent enucleation and orbital expansion at a near-normal physiologic pressure of 20 mmHg. Group 3 (n = 5) underwent enucleation and orbital expansion at a supernormal pressure of 60 mmHg. Spherical tissue expanders (10 cc) with a separate injection port were utilized as the orbital expanders. Pressure was monitored by an electronic manometer that was calibrated daily. Morphology of the orbits was documented by photography, the dimensions of the orbits were quantitated by three-dimensional mechanical digitization, and orbital volumes were calculated. In the unexpanded, anophthalmic control group, a significant reduction in radial growth after evisceration was seen. In group 2, the orbit stimulated with a consistent pressure of 20 mmHg, just above the physiologic normal pressure of 17 mmHg, showed an increase in radial dimension of 8 percent compared with the unoperated side. In the high-pressure group of 60 mmHg, an increase of 16 percent in the radius was observed over the 4-week period. This led to a corresponding increase in orbital volumes with increased pressure. Utilizing a paired t test, these differences in the radial and volumetric growth of the orbit were statistically significant (p < 0.005). The results obtained demonstrated a direct relationship between intraorbital pressure and the growth of the bony orbit in the radial dimension. On the basis of this study, we concluded that orbital expansion maintained at normal physiologic pressure can stimulate normal orbital growth in the neonatal facial skeleton. In addition, application of above-normal pressures for expansion can induce accelerated orbital growth.

A rational algorithm for duplex scan surveillance after carotid endarterectomy

Purpose: This study was undertaken to determine the appropriate timing and frequency of duplex ultrasound scanning after carotid endarterectomy (CEA) for the detection of high-grade stenosis caused by recurrent carotid stenosis or contralateral atherosclerotic disease progression. Methods: In 221 patients who underwent 242 CEAs, duplex scanning was performed before, during, and after operation (in 3-month to 6-month intervals). High-grade internal carotid artery (ICA) stenosis (peak systolic velocity, >300 cm/s; diastolic velocity, >125 cm/s; ICA/common carotid artery ratio, >4) prompted the recommendation for repair. An average of four postoperative scanning procedures was performed during a mean follow-up period of 27.4 months. Results: Intraoperative duplex scan results prompted the immediate revision of 12 repairs (4.9%), and one perioperative stroke (<1%) occurred. Six CEAs (2.7%) had asymptomatic recurrent stenosis (>50% diameter-reduction [DR]; systolic velocity, >125 cm/s) develop. Only one of six patients had >75% DR stenosis develop and underwent reoperation (<1% yield for CEA surveillance). The yield of surveillance of the unoperated ICA was higher ( P = .003), and 12% of unoperated sides had progressive stenosis (n = 21) or occlusion (n = 3) develop, which led to seven CEAs for high-grade stenosis. Disease progression to >75% DR stenosis was five times as frequent ( P =.002) in patients with >50% DR stenosis initially. All patients but one who required contralateral endarterectomy for disease progression had >50% ICA stenosis when first seen. During the follow-up period, no disabling strokes ipsilateral to an operated carotid artery occurred, but three strokes occurred in the hemisphere of the contralateral unoperated ICA. Conclusion: The yield of duplex scan surveillance after CEA was low. Only 13 patients (5.9%) had severe disease develop to warrant additional intervention. Progression of contralateral disease rather than restenosis was the most common abnormality that was identified. Duplex scanning at 1-year to 2-year intervals after CEA is adequate when a technically precise repair is achieved and minimal contralateral disease (<50% DR) is present. A policy of duplex scan surveillance and reoperation for high-grade stenosis was associated with a 1.6% incidence rate of disabling stroke during the follow-up period. (J Vasc Surg 1999;30:453-60.)

Transient effects of nerve injury on estimates of sensory neuron number in juvenile bullfrog

The effect of lumbar spinal nerve (SN) transection on estimates of neuron number was investigated in the dorsal root ganglia (DRGs) of juvenile bullfrogs (Rana catesbeiana). SN8 and SN10 were transected on one side, and SN9 was left intact. Two weeks after nerve injury, estimates of neuron number in DRG8 and DRG10 on both the operated and unoperated sides were more than twice the estimates obtained from control animals. Neuron number in the uninjured DRG9 was also elevated relative to that of control animals. Eight weeks after axotomy, differences in neuron number were less apparent. The mean cross-sectional area of DRG neurons was reduced 2 weeks after nerve injury in all DRGs. The decrease in mean area was the result of the addition of neurons to the smallest size classes. These data are discussed in the context of previous results showing that neurons are added as juvenile frogs grow to adult size (St. Wecker and Farel [1994] J. Comp. Neurol. 342:430-438). This addition results from the maturation of a population of incompletely differentiated neurons (Meeker and Farel [1997] J. Comp. Neurol. 389:569-576). The present results suggest that axotomy precipitates differentiation of these incompletely differentiated neurons, perhaps as a compensatory response to nerve injury.

Effects on acetabular development of resection of the labrum acetabulare (limbus) in the hip joint.

The effect of resecting the hip joint limbus on acetabular development was studied. Ten infant Japanese monkeys were used as experimental subjects. The limbus was resected on one side and the developmental effects were observed. The period of observation ranged from 12 to 31 months with a mean of 17 months. After histological examination of the resected limbus, the monkeys were divided into two groups, group A (5 cases) in which the hyaline cartilage had not been resected, and group B (5 cases) in which the hyaline cartilage had been resected. Every 2 months after the operation, each monkey was x-rayed and the acetabular angle, acetabular index, acetabular edge angle and Wiberg's Center-Edge angle were measured and the differences between the resected and unoperated sides were subjected to regression analysis. Neither Group A nor Group B developed acetabular dysplasia.

A critical role for the optic vesicle in lens development; A reinvestigation of free lens formation in Cynops pyrrhogaster

The role of the optic vesicle in lens development was reinvestigated in Cynops pyrrhogaster. To study the necessity for the optic vesicle in early lens development, the optic anlages of stage 17–27 embryos were ablated and the frequency of free lens formation was examined with lens specific markers. Free lens formation was not observed when operations were performed prior to contact between the head surface epidermis and the optic vesicle (stages 17–18). On the contrary, free lens formation occurred in all cases where the optic vesicles were removed after the initiation of lens placode formation in the head surface epidermis (stage 27). However, no lens fiber formation was observed in these free lenses as judged by the absence of lens fiber specific gene expression, namely γ-crystallin, at stages when secondary lens fiber formation could be found in the control lenses of the unoperated sides. The pattern of expression of αA-crystallin in the developing free lens also differed from that of the normally developing lens. This paper is the first report to indicate that the coordinated and sequential expression of crystallin genes are influenced by the optic vesicle; the optic vesicle is required for proper regulation of the αA- and γ-crystallin but not βB1-crystallin genes.

Effects of Restrained Fetal Movement on the Development of the Rat Hip Joint

ABSTRACTThe effect of fetal movement on the development of the hip joint was examined by restraining the leg movement using exo utero operation in rat fetuses. At embryonic day (E) 16.5, when the hip joint cavity starts to form, one side of the hind limb was sutured onto the embryonic membrane. After exo utero development to E18.5, the hip joint of the operated side was compared morphologically with those of the unoperated side, sham‐operated and unoperated in utero controls. The largest diameter of the femoral head (FH) and the gross morphology of the joint cavity of the operated side was not different from those of controls. By light microscopy (LM), the surface of the control E18.5 FH and acetabulum was smooth and covered by thin scale‐shaped cells which were partially pyknotic, and oval‐shaped cells underneath were rather regularly arranged in a thickness of a few cells. By transmission electron microscopy (TEM), scale‐shaped cells covered the FH surface incompletely, and the spaces in‐between were filled with the intercellular matrix. Oval‐shaped cells underneath had well developed rough endoplasmic reticulums. By scanning electron microscopy (SEM), mounds and grooves on the FH surface were evident at E17.0 but became unclear at E18.5. Subsurface collagen fibers formed a coarse meshwork at E17.0 but formed bundles at E18.5. On the operated side, by LM, the surface of the FH and acetabulum was irregular and lined by spindle‐shaped cells, whereas the underlying mesenchymal cells also showed an irregular cell shape and arrangement. By TEM, collagen fibrils in intercellular spaces were dense but did not generally form bundles. By SEM, the FH surface was rugged with banks and subsurface collagen fibers did not form bundles but remained as a dense meshwork. These results suggest that the fetal hind limb movement influences development of the surface structure of the FH and acetabulum and that this system may be useful to study prenatal etiology of the congenital dislocation of the hip.

Bulbectomy of neonatal mice induces migration of basal cells from the olfactory epithelium

Bulbectomy of neonatal mice induced cell migration from the olfactory epithelium in the nasal septum. We examined cell types of migrating clusters by immunohistochemistry using anti-keratin and anti-BrdU antibodies, and by electron microscopy. At 1–2 days after unilateral bulbectomy of P1 mice, cells migrated from the olfactory epithelium to the lamina propria of the septal olfactory mucosa. Horizontal basal cells that reacted specifically with anti-keratin antibody, and globose basal cells characterized by a round shape and poor content of organellae in their cytoplasm, were contained in the cluster. At 1 week, migrated clusters that contained keratin-positive horizontal basal cells were observed in both the lamina propria and olfactory bulb on the unoperated side. At 1 month, not only basal cells but also olfactory cells and presumed supporting cells were involved in the clusters in the lamina propria and olfactory bulb, suggesting that migrated cells do not transform to other phenotypes.

An enhanced olfactory marker protein immunoreactivity in individual olfactory receptor neurons following olfactory bulbectomy may be related to increased neurogenesis

Olfactory marker protein (OMP) is a 19-kD acidic protein found throughout the cytoplasm of mature olfactory receptor neurons (ORNs). Its function remains unknown. Following olfactory bulbectomy, the proportion of ORNs mature enough to express OMP declines greatly. However, in the few remaining mature ORNs, it has been observed that the intensity of OMP immunoreactivity (IR) appears to increase over that of ORNs on the unoperated side. We have now investigated this phenomenon quantitatively in rats subjected to unilateral olfactory bulbectomy. Results show that at all postbulbectomy survival periods examined quantitatively (3 days to 6 months), a significant decrease (19-37%) occurs in the transmission of incident light through OMP(+)-ORNs in bulbectomized versus unoperated olfactory epithelium (OE). Further, we also observed a consistent side-to-side difference in OMP IR in control unoperated animals. Possible explanations for these observations and their relation to the still unknown function of OMP are discussed. To test the possibility that OMP might serve a mitogenic role in the OE, recombinant OMP was added to organotypic explant cultures of fetal olfactory mucosa. Addition of OMP resulted in a dose-dependent increase in the density of bromodeoxyuridine-positive cells in the cultures, with a 50% increase occurring at the plateau OMP concentration of 25 pM.

The effects of arthroscopic acromioplasty on the acromioclavicular joint

Thirty patients with 31 shoulders underwent clinical and radiologic evaluation 5 to 6 years after arthroscopic acromioplasty. The mean age was 51 years. The acromioclavicular (AC) joint was assessed for tenderness on palpation and pain on horizontal adduction of the shoulder. All patients underwent a radiologic examination consisting of an anteroposterior view of the AC joint and bilateral stress views. No patient had superior translation or widening of more than 1 mm of the AC joint on stress views on the unoperated side. On the operated side 12 (38%) shoulders showed signs of instability consisting of a superior translation of the clavicle of 2 to 3 mm, distraction on weight bearing view, or both. No severely osteoarthritic AC joint (grade 3 or 4) was unstable. The degree of osteoarthritis did not differ for both shoulders, suggesting that arthroscopic acromioplasty does not accelerate osteoarthritic change in the AC joint but can induce instability. Nine patients had tenderness over the AC joint and instability on stress views. They had a significantly reduced University of California Los Angeles score of 25 ± 5 compared with the other patients (29.5 ± 7). We conclude that preservation of the inferior capsule during arthroscopic acromioplasty is important for the integrity of the AC joint in patients without severe osteoarthritic changes.

Ultrastructural localization of immunoglobulin G and complement C9 in the brain stem and spinal cord following peripheral nerve injury: an immunoelectron microscopic study.

The ultrastructural localization of immunoreactivity for immunoglobulin G (IgG), F(ab')2 and complement C9 was examined with preembedding immunoelectron microscopy in the hypoglossal nucleus and gracile nucleus as well as in the L4 spinal cord dorsal horn 1 week following hypoglossal or sciatic nerve transection, respectively. Only a few scattered immunoreactive profiles were observed on the unoperated side. On the operated side, IgG and F(ab')2 immunoreactivity was present in the membranes of all reactive microglial cells observed. In addition, the cell membrane of some hypoglossal motoneurons showed IgG immunoreactivity. Complement C9 immunoreactivity was present in the cytoplasm of all reactive microglial cells examined. In addition, there was diffuse C9 immunoreactivity in motoneuron perikarya ipsilateral to nerve injury as well as in cell membranes in the neuropil, some of which could be identified as neuronal. Our interpretation of these findings is (1) that peripheral nerve injury results in binding of IgG to reactive microglia, as well as to some axotomized neurons, and (2) that C9 is synthesized by reactive microglia in response to axon injury and is also associated with axotomized motoneurons. These findings suggest that IgG and complement C9 are involved in microglia-neuron interactions after peripheral nerve injury.

Quantitative studies of nuclear bodies in astrocytes of chicken spinal cord following axotomy.

The present study was designed to reveal whether astrocytic activation following axotomy causes a numerical increase of nuclear bodies (NBs) in chicken astrocytes. Astrocytes in the spinal cord were activated by a unilateral spinal nerve transection. The frequency of NBs was calculated at the lateral motor columns of the normal group and at the ipsi- and contralateral sides of operated group. In the growing chickens, NBs of each astrocyte were a few and decreased steadily in number with age. In the operated chickens, the frequency of NBs elevated temporarily both in the ipsi- and contralateral sides, and reached its maximum value by 30 post-operative days. The frequency of NBs increased more prominently in the operated side than in the unoperated side. Thus, the present study provides the first evidence for a significant increase in the number of NBs in the hyperactive astrocytes caused by axotomy.

Expression of glutamate receptor subunits 2/3 and 4 in the hypoglossal nucleus of the rat after neurectomy.

The immunoreactivity of glutamate receptor subunits 2/3 (GluR2/3) and 4 (GluR4) was studied following neurectomy of the hypoglossal nucleus (NH). After a short period of survival (at 1, 2, and 7 days postoperation, dpo), GluR2/3 immunoreactivity was barely dectectable in the operated side of HN. During these periods, GluR4 immunoreactivity was present, but was greatly reduced when compared with the GluR4 immunoreactivity in the unoperated side. The data suggest that of the 4 subunits of the AMPA receptor, GluR2/3 is the most susceptible receptor to the early stage of hypoglossal neurectomy, and GluR4 tolerated the lesion more than the others. It is also suggested that both GluR2/3 and 4 may play a very important neuroprotective role in the early stage of neuronal degeneration after axotomy, especially the former. Following a midterm survival period (14, 21, and 35 dpo), GluR2/3 immunoreactivity gradually reappeared in some neurons on the operated side of HN, which may indicate functional recovery. However, the number of GluR4-immunopositive neurons on the operated side of HN was greatly reduced. The reason for such a reduction is not known, but, from the speculative point of view, it is possible that the disappearance of GluR4-positive neurons may be related to their excitotoxic property, especially at 35 dpo, when neuronal cell death had already occurred. Following a long-term period of survival (i.e., 56, 90, and 120 dpo), the numbers of surviving neurons remained fairly constant, suggesting the possible cessation of neuronal death.

Mandibular osteotomy fixed with biodegradable plates and screws: an animal study

The objective of the study was to evaluate the use of a totally biodegradable fixation device in the fixation of mandibular osteotomy in sheep. Mandibular unilateral body osteotomies were fixed with biodegradable self-reinforced poly-L-lactide (SR-PLLA) multi-layer plates and screws in nine sheep. The unoperated sides acted as control. The follow-up times were 6, 12 and 24 weeks, after which radiological, mechanical and histological studies were carried out. An analysis of the implanted material was also carried out. The results showed that the SR-PLLA plates and screws were strong enough to fix the osteotomy and that the osteotomies healed mainly with callus formation. Therefore we conclude that SR-PLLA multi-layer plates and screws can be used together successfully in the fixation of mandibular osteotomies without maxillomandibular fixation. However, before they can be used in humans, the size of the plate and screws should be decreased.

The reorganization of μ opioid receptors in the rat dorsal horn following peripheral axotomy

The μ opioid receptor is concentrated in laminae I and II (LI and LII, respectively) of the normal rat dorsal horn. Fourteen days after transection of the L4–L6 segmental peripheral nerves, image analysis demonstrates a 49, 34 and 17% decrease in μ opioid staining density in the medial, middle and lateral thirds of the superficial dorsal horn, respectively, when comparing the operated to the unoperated side. Intralaminar analysis demonstrates that the greatest change in density occurs in LI and LII outer, compared to LII inner. By 31 days post-surgery, staining has returned to normal with side to side differences no longer present. These results imply that μ opioid ligands such as morphine might be less effective in ameliorating pain 2 weeks after a peripheral nerve lesion than they are in the normal condition, but that this effectiveness should return as the receptors are restored to their normal levels. Thus, the time following a lesion may be an important variable in assessing the effectiveness of μ opioid ligands in alleviating neuropathic pain. Furthermore, this study shows that the organization of opioid receptors in the superficial dorsal horn is malleable and could lead to changes in drug efficacy.

Decreased neuronal nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in rat pterygopalatine ganglion parasympathetic neurons and cerebrovascular innervation following long-term sympathectomy

Neural control of tissue perfusion is mediated predominantly by sympathetic vasoconstrictor and, in some tissues, parasympathetic vasodilator systems. The objective of this study was to determine if changes occur within parasympathetic vasodilator neurons supplying cranial vessels after sympathectomy. Cranial sympathetic innervation was excised unilaterally, and 6 weeks later pterygopalatine ganglion neurons were evaluated for expression of neuronal nitric oxide synthase immunoreactivity (NOS-ir) and NADPH-diaphorase activity. Relative to the unoperated side, the number of parasympathetic neurons staining densely either for NOS or for NADPH-diaphorase decreased by 37% and 47%, respectively, whereas unstained somata increased by 51% and 48%. Internal carotid artery NOS-ir innervation density was reduced by 35%. These findings are consistent with a down-regulation of nitrergic properties in some cranial parasympathetic neurons after sympathectomy.

Expression of Glutamate Receptor Subunit 1 and Nitric Oxide Synthase in the Hypoglossal Nucleus and Dorsal Vagal Nucleus in the Rat After Neurectomy

Using nitric oxide synthase (NOS) and glutamate receptor subunit 1 (GluRl) immunohistochemistry. the present study demonstrated changes in the expression of NOS and GluR 1 in the hypoglossal (HN) and dorsal vagal nucleus (DVN) after neurectomy. Two and 7 days after sectioning the left hypoglossal nerve, NOS expression was seen in a few neurons but GluRl immunoreactivity was drastically reduced in the ipsilateral HN. The upregulation of NOS immunoreactivity in the HN appeared to peak at 14 days postoperation (dpo). At this period, however, the GluRl immunoreactivity almost completely disappeared. Twenty-one, 35 and 56 days after neurectomy, NOS immunoreactivity was still expressed in the ipsilateral HN; at the same time, GluRl immunoreactivity reappeared in a few neurons of the nucleus. Ninety days after operation, NOS immunoreactivity completely disappeared on the operated side of the nucleus, but GluRl immunoreactivity was re-expressed in many hypoglossal neurons. The number of such neurons was obviously less than that on the unoperated side. After sectioning the left vagus nerve in the same animals, the expression of NOS immunoreactivity in the ipsilateral DVN resembled that in the HN. on the unoperated side, NOS immunoreactivity was demonstrated in some neurons in the DVN, like that in the normal. In both normal and operated rats, only a few neurons expressed GluRl immunoreactive products on both the operated and unoperated sides of the DVN. Combining with previous results on protein synthesis observed at 14 dpo, the present investigation suggested that in the early stages after neurectomy, the expression of NOS immunoreactivity and loss of GluRl expression in the HN may indicate the organism's double protective mechanism. Lastly, the reappearance of GluRl in the same nucleus from 21 to 90 days after operation may reflect functional recovery of the hypoglossal neurons.

Evidence that intersegmental competition influences the segmental distribution of the central terminals of muscle sensory afferents in the chicken embryo

The possibility that muscle sensory afferents that enter the spinal cord at different segmental levels compete for terminal space in the lateral motor column was tested by unilaterally ablating neural crest cells destined to generate dorsal root ganglia (DRGs). Newly migrating neural crest was surgically removed from several lumbosacral segments on one side of the spinal cord on day 3 of embryogenesis (d3). The resultant experimental preparations developed without DRGs on the operated side at the segmental levels where the ablation was performed. At d18 the central projection from the intact DRG immediately caudal to the operated segments was anatomically mapped with a lipophilic axonal tracer. The central projection from the same DRG on the opposite, unoperated side was mapped as a control. The density of terminals along the longitudinal axis of the lateral motor column was quantified in serial sections with an image analysis program. On both the operated and control sides, the majority of terminals were found within the segment of entry and the rostral and caudal neighboring spinal segments. However, the rostral neighboring segment received a larger proportion of terminals on the operated side compared to the control side. Thus, the absence of primary afferents entering the spinal cord at specific segments leads to a shift of the afferent projection to the lateral motor column from the neighboring segments towards the deafferented segments.

Chick auditory terminals contain dynorphin-like immunoreactivity.

Dynorphin-like immunoreactivity (DYN-I) was studied in the auditory brain stem of chick hatchlings using an antiserum to dynorphin-B. DYN-I was found in a few small cells in the nucleus laminaris (NL) and in the superior olive (SO). Dendrites in NL also appeared immunostained. DYN-I, however, was especially prominent in the cochlear nucleus magnocellularis (NM). A few DYN-I somata could be found within NM particularly in medial regions of this nucleus. Most DYN-I, however, was localized to calyceal-type structures, reminiscent of primary auditory nerve terminals, surrounding nerve cell bodies in NM. To determine whether DYN-I is contained within auditory end-bulbs of Held, the basilar papilla (avian cochlea) was removed unilaterally. After 5 days survival, there were very few DYN-I terminals in NM on the operated side of the brain compared with the unoperated side. This novel finding suggests that primary auditory nerve terminals in NM may contain the opioid peptide, dynorphin.