An assessment of the replicability of a standard and modified sanitary risk protocol for groundwater sources in Greater Accra.

Sanitary risk inspection, the systematic observation of contamination hazards, is often used to manage safety of water sources such as wells and boreholes. However, the replicability of sanitary risk inspections undertaken by different observers has not been studied. This study aimed to assess the replicability of sanitary risk inspections by two different observers in urban and peri-urban neighbourhoods of Greater Accra, Ghana. Two observers independently used a standard protocol to record contamination hazards around 62 groundwater sources, additionally recording urban-specific hazards such as damaged sewage pipes via a modified protocol. We calculated risk scores as the proportion of hazards observed at each source, separately for each observer. Linn's concordance correlation coefficient indicated very high agreement between the two observers' risk scores (n = 62; c = 0.949, 95% confidence limits 0.917-0.968). However, risk scores from urban-specific observations were uncorrelated with those from the standard protocol (r = 0.11, p = 0.41 for observer 1; r = 0.16, p = 0.22 for observer 2). Ours is the first study of replicability of sanitary risk observations and suggests high inter-observer agreement. However, urban contamination hazards were not captured using the standard protocol. In the future, assessment of inter-observer agreement and observations of urban-specific hazards could be incorporated into nationwide or regional sanitary risk surveys.

Biological effects of gold mine tailings on the intertidal marine environment in Nova Scotia, Canada.

From 1861 to the 1940s, gold was produced from 64 mining districts in Nova Scotia, where mercury amalgamation was the dominant method for the extraction of gold from ore until the 1880s. As a result, wastes (tailings) from the milling process were contaminated by mercury and were high in naturally occurring arsenic. In 2004 and 2005, sediments, water and mollusc tissues were collected from 29 sampling stations at nine former gold mining areas along the Atlantic coastline and were analysed for arsenic and mercury. The resulting data were compared with environmental quality guidelines. Samples indicated high potential risk of adverse effects in the intertidal environments of Seal Harbour, Wine Harbour and Harrigan Cove. Arsenic in Seal Harbour was bioavailable, resulting in high concentrations of arsenic in soft-shell clam tissues. Mercury concentrations in tissues were below guidelines. This paper presents results of the sampling programs and implications of these findings.

Effects of glyphosate-based herbicides on survival, development, growth and sex ratios of wood frogs (Lithobates sylvaticus) tadpoles. I: chronic laboratory exposures to VisionMax®.

The purpose of this study was to determine if chronic exposure to the glyphosate-based herbicide VisionMax(®) affects the survival, development, growth, sex ratios and expression of specific genes involved in metamorphosis of wood frog tadpoles (Lithobates sylvaticus). We hypothesized that exposure to this herbicide will affect developmental rates by disrupting hormone pathways, sex ratios and/or gonadal morphology. Tadpoles were chronically exposed in the laboratory from Gosner developmental stage 25 to 42 to four different concentrations of VisionMax(®) (ranging from 0.021 to 2.9 mg acid equivalents/L). Chronic exposures to VisionMax(®) had direct effects on the metamorphosis of L. sylvaticus tadpoles by decreasing development rates, however, there was a decrease in survival only in the group exposed to the highest dose of VisionMax(®) (2.9 mg a.e./L; from approximately 96% in the control group to 77% in the treatment group). There was a decrease in the number of tadpoles reaching metamorphic climax, from 78% in the control group to 42% in the VisionMax(®) (2.9 mg a.e./L) group, and a 7-day delay to reach metamorphic climax in the same treatment group. No effects of exposure on sex ratios or gonadal morphology were detected in tadpoles exposed to any of the concentrations of VisionMax(®) tested. Gene expression analyses in brain and tail tissues demonstrated that exposure to VisionMax(®) alters the expression of key genes involved in development. Results showed significant interaction (two-way ANOVA, P<0.05) between developmental Gosner stage and treatment in brain corticotropin-releasing factor, deiodinase type II (dio2) and glucocorticotiroid receptor (grII) and tail dio2 and grII. This demonstrates that mRNA levels may be differently affected by treatment depending on the developmental stage at which they are assessed. At the same time there was a clear dose-response effect for VisionMax(®) to increase thyroid hormone receptor ß in tadpole brain (F(2,69)=3.475, P=0.037) and tail (F(2,69)=27.569, P<0.001), regardless of developmental stage. Interestingly, delays in development (or survival) were only observed in the group exposed to 2.9 mg a.e./L of VisionMax(®), suggesting that tadpoles need to be exposed to a "threshold" concentration of glyphosate-based herbicide to exhibit phenotypic observable effects. We suggest that the upregulation of genes that trigger metamorphosis following VisionMax(®) herbicide exposure might result from a compensatory response for the delays in development observed. Further studies are needed to determine if disruption of expression of these key genes leads to long-term effects when metamorphs reach adult stages.

Antibody against chromatin assembly factor-1 is a novel autoantibody specifically recognized in systemic lupus erythematosus.

Autoantibodies to proliferating cell nuclear antigen (PCNA) are specifically, if rarely, present in systemic lupus erythematosus (SLE) patient sera. Even SLE patients lacking PCNA reactivity often show reaction to PCNA-binding protein. Here, immunoreactivity to chromatin assembly factor-1 (CAF-1), an essential molecule for DNA replication and a PCNA-binding protein, was compared for the sera of SLE patients, normal healthy controls (NHCs) and other disease controls, and in autoimmune sera reactive to standard autoantigens, by enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence, and immunoblotting. CAF1 and IRF1 expression in SLE and NHC peripheral mononuclear cells were compared by quantitative real-time polymerase chain reaction. Serum interferon-γ-inducing protein-10 and anti-double-stranded (ds)DNA antibody levels were measured by ELISA. Increased CAF-1 autoimmune reactivity was recognized in SLE or serum anti-dsDNA antibody-positive patients. Significantly greater central nervous system (CNS) involvement (aseptic meningitis) and serum anti-dsDNA antibody titers were present more often in anti-CAF-1 antibody-positive than antibody-negative SLE patients. IFN-γ positively regulated CAF-1 expression in vitro and was associated with anti-CAF-1 antibody production in SLE. Thus, a novel anti-CAF-1 autoantibody is frequently found in patients with SLE and is a useful biomarker for diagnosis, especially in cases with CNS involvement. Aberrant IFN-γ regulation appears to play an important role in anti-CAF-1 antibody production in SLE.

Evaluation of buffer zone effectiveness in mitigating the risks associated with agricultural runoff in Prince Edward Island.

To minimize the risk posed by runoff from row crops, Prince Edward Island introduced buffer legislation in 2000. The legislation mandates 10-m and 20-m buffers, respectively, for moderate sloped (i.e. <5%) and steep sloped (i.e. >5%) agricultural fields that border streams. Since 2001, Environment Canada has been evaluating the effectiveness of various buffer widths on operational farms in reducing toxicity and contaminant concentrations in runoff. Sample collectors, placed in 44 fields at the field edge (0m), 10m and at distances out to 30m, collected overland flow following rainfall-induced runoff events. Samples were collected within 24 hours of an event and analysed for seven pesticides (endosulfan, chlorothalonil, carbofuran, linuron, metribuzin, metalaxyl, mancozeb), water quality parameters and Daphnia magna toxicity. The 10-m buffer required for moderate sloped fields was effective at reducing contaminant concentrations but not always to less than lethal concentrations to Daphnia magna. Limited data beyond 10m for fields of both slope types precluded making recommendations on a suitable buffer width for shallow sloped fields and evaluating the effectiveness of 20-m buffers for steep sloped fields. When paired data were combined and statistically tested for all fields, the studied pesticides underwent a 52-98% and 68-100% reduction in aqueous and particulate concentrations within 10m and 30m, respectively. In addition, by 10m, soluble phosphorus, nitrate-nitrogen and total suspended solids were reduced by 34%, 38% and 64%, respectively. Results suggest buffer zones on operational farms are capable of achieving contaminant reductions comparable to those reported for controlled experiments. Inconsistent siting of sample collectors beyond 10m limited the evaluation of the effects of field slope and buffer width on buffer effectiveness on working farms. Future studies on buffer efficiency on operational farms should focus on building the data set beyond 10m and evaluating load reductions.

[Intraorbital dermoid cyst: case report]. / Kyste dermoïde intraorbitaire: un cas.

Dermoid cysts account for 3-4 % of primary orbital tumors. The intraorbital location is relatively rare. The authors report a case of a 12-year-old male with an intraorbital dermoid cyst revealed by progressive right proptosis. The imaging aspects (CT scan and MRI) were consistent with intraconic dermoid cyst. The tumor was extirpated via a subfrontal approach. Histopathologic examination confirmed the diagnosis of dermoid cyst. The authors discuss the clinical symptoms, radiological aspects, and management.

[Neurosurgical management of paraplegia complicating Pott's disease: a six-case study]. / Prise en charge neurochirurgicale de la paraplégie tuberculeuse : à propos de six cas.

Tuberculosis is a rare disease in economically developed countries. Paraplegia is one of its severe complications, occurring in cases of spondylodiscitis with compressive epiduritis and/or pathological fracture of vertebral bodies with subacute kyphosis. Six patients aged 15-75 years were treated in our department from May 2005 to April 2006 by the same operator (L.N.) for paraplegia complicating Pott's disease. Patients' neurologic function at admission and their outcomes three and 12 months after surgery were graded using the Frankel classification. MRI showed a single lesion in five cases and skip lesions in one case. Standard antituberculosis chemotherapy was started immediately within the first week of admission in five patients following a 12-month regimen. Principles of surgical treatment were ventral spinal cord decompression (with or without dorsal stage procedure), immediate grafting, correction of subacute spinal deformity and instrumentation in all cases. The diagnosis of Mycobacterium tuberculosis was confirmed by laboratory investigations in four cases and by histopathological examination in all cases. One patient who had undergone prior isolated laminectomy performed by an on call team presented neurological deterioration and progressive kyphosis. Neurological outcome improved in five patients. Four of them were able to walk unaided within the first three months after surgery. No perioperative complication occurred. In paraplegia complicating vertebral tuberculosis, overall neurological outcome appeared to be good in case of delayed emergency surgical management combined with antituberculosis chemotherapy.

[Cervicomanubrial route for the ventral upper thoracic spine: technical note about six cases]. / Abord ventral transcervicomanubrial du rachis thoracique supérieur: note technique à propos de six cas.

Ventrolateral cervicotomy provides a narrowed working space for surgical management of upper thoracic spine. We report our experience about ventral upper thoracic spinal cord decompression with reconstruction and plating via the cervicomanubrial route. Six patients (24 to 75 years old) were operated on by the same operator (LN) by cervicomanubriotomy from 2002 to 2007 for upper thoracic spinal cord compression (one case of Pott's disease, three cases of metastases, one fracture, one invasive hemangio-epithelioma), with a good outcome in five patients. Lesions were located from the cervicothoracic junction down to the fourth thoracic vertebra (T4). In all cases, anterior spinal cord decompression, strut graft reconstruction (iliac bone in two cases, cement in four cases) and osteosynthesis were performed. In two cases, a second stage posterior decompression with fixation was performed. The approach begins by a left sided anterior cervicotomy, medial to the sternocleidomastoid muscle and lateral to the trachea and esophagus, associated with division of the infrahyoid muscles close to their insertion at the upper thoracic outlet followed by osteotomy of the manubrium sterni. Then, division of the thyropericardic fascia and thymus, control of the brachiocephalic vein, control of the thoracic lymphatic duct and the horizontal thoracic aorta are performed. The ventral part of fifth cervical vertebra body down to T4 is then exposed between the left primitive carotid artery laterally, the esophagus medially and the thoracic aorta caudally. Compared to total sternotomy without or with clavicle resection, cervicomanubriotomy seems to be a less aggressive, safe and reliable procedure.

Arsenic bioaccessibility and speciation in clams and seaweed from a contaminated marine environment.

The bioaccessible concentration and speciation of arsenic (soluble in a gastrointestinal medium and available for absorption into the bloodstream) were determined in softshell clams (Mya arenaria), harvested by local residents until 2005, and in seaweed (Fucus sp.) from an arsenic-contaminated marine site in Seal Harbour, Nova Scotia, Canada. Bioaccessibility extractions to simulate the human gastrointestinal environment (pH 1.5 and glycine for 1h followed by pancreatin, bile extract and pH adjustment to 7 for an additional 4h) and speciation of arsenic in extracts (HPLC-HG-AAS to target inorganic arsenic species) and whole samples (XANES) were carried out. Total arsenic for the clams from the contaminated area ranged from 218 to 228 ppm wet weight, with a bioaccessible fraction of 34-46%, and the major bioaccessible species of arsenic were inorganic. The seaweed from the contaminated area contained 27-43 ppm wet weight total arsenic, with the bioaccessible fraction ranging from 63% to 81%, and inorganic arsenic was also predominant. The predominantly inorganic nature of arsenic in the whole samples was confirmed by XANES. In concurrence with the closure of the area for clam harvesting, the clams and seaweed from Seal Harbour should probably not be used for human consumption.

[Emergency surgery of a large ruptured arteriovenous malformation previously treated by several embolization procedures]. / Intervention en urgence après rupture d'une malformation arterio-veineuse intracérébrale complexe embolisée à plusieurs reprises.

A 56-year-old patient with a giant parieto-occipital left-sided arteriovenous malformation (AVM) revealed by seizure was treated by four embolization procedures. Stereotactic radiosurgery was scheduled for the residual nidus but significant intracranial hemorrhage occurred and surgical excision had to be performed. The immediate post-operative status was precarious, but the final outcome was successful. Therapeutic indications are discussed. A multidisciplinary approach for judicious patient selection is surely the key to safe overall management of AVMs.

[Dialysis-associated spondyloarthropathy. Case report and literature review]. / La spondylarthropathie érosive du dialysé rénal. A propos d'un cas, revue de la littérature.

Hemodialysis has considerably prolonged the life of patients suffering from terminal renal failure. However, long-term hemodialysis leads to new bone complications and spinal disorders such as destructive spondyloarthropathy (DSA). At the present time DSA is reported in 8% to 18% of the dialysed patients. Diagnosis is based on severe narrowing of the intervertebral disk, erosions and geodes of the adjacent vertebral plates simulating infectious spondylitis. Lesions progressively involve posterior joints and may lead to severe destruction of the spine. The pathogenesis of this syndrome is still unknown. Several factors have been implicated, including microcrystal deposition, amyloidosis, inflammatory and foreign body reactions and suggest that the pathogenesis of erosive spondyloarthropathies of hemodialysed patients is multifactorial. Spinal instability inducing myelopathy and radiculopathy were observed in 8% of the cases. Treatment must be accorded to the natural disease course and to the quality of the bone. We report the case of a chronic dialysed patient with destructive spondyloarthropathy involving the cervical and thoracic spine. Pathogenesis, radiological datas and therapeutic approach are discussed.

[Chronic lower back pain: a new therapeutic approach]. / Lombalgies chroniques: une autre approche thérapeutique.

Lower back pain is a common complaint of patients seen in our consultations. Despite progress, surgical procedures are still often unsuccessful in relieving pain. Blocks performed in the epidural spaces or more often in the articular facets have provided poor relief of chronic lower back pain. The pain has vegetative components. Considering anatomic findings, we describe the innervation of the peridiscal tIssues which suffer during degenarative conditions. We analyze the course of the autogenic nerves mediating lumbar pain, and select the site of the blocks necessary to obtain optimal selective pain relief. A well-defined block at the level of the communicating rami is described.

[Cervical medullary metastasis in a patient with Von Hippel-Lindau disease]. / Métastase médullaire cervicale au cours d'une maladie Von Hippel-Lindau .

Von Hippel-Lindau disease is an autosomal dominant disorder mainly characterized by hemangioblastoma(s) associated with kidney clear-cell carcinoma. Hemangioblastoma represents 2 to 3% of all central nervous system tumors whereas extramedullary metastasis accounts for 30 to 50% of all intravertebral column tumors. The most common sites of metastatic dissemination in order of frequency are the lung, breast, prostate and kidney. We report a case of an unusual cervical intradural extramedullary metastasis of clear-cell kidney carcinoma associated with a cervical spinal cord hemangioblastoma in a 45-year-old patient with Von Hippel-Lindau disease who had developed retinal hemangioblastomas 20 years earlier. A review of the relevant literature is proposed.

Dispersion and toxicity to non-target aquatic organisms of pesticides used to treat sea lice on salmon in net pen enclosures.

Pesticides are used extensively in the finfish aquaculture industry to control sea lice infestations on farmed salmon. The most prevalent method of use is to enclose a net pen with an impervious tarpaulin and mix a pesticide solution within that enclosure. After treatment for short periods (1 h) the pesticide solution is released to the environment. Concerns have been raised that there is a potential risk to non-target aquatic organisms from those releases. The fate of dispersing pesticide solutions was measured after six simulated treatments in the Lower Bay of Fundy, New Brunswick. Three simulated treatments were done with azamethiphos and three with cypermethrin. Rhodamine dye was added to all pesticide solutions in order to facilitate tracking of the dispersing plume through real-time measurements of dye concentrations by a flow-through fluorometer coupled with a differential global positioning system (DGPS). Water samples were obtained from within the plumes at various times after release and analysed for pesticide content and toxicity to a benthic amphipod Eohaustorius estuaris. Dye concentrations were detectable for time periods after release which varied from 2 to 5.5 h. Distances travelled by the dye patches ranged from 900 to 3000 m and the dye concentrations at the final sampling period were generally 1/200-1/3000 the pre-release concentrations and cypermethrin concentrations were generally 1/1000-1/2000 the pre-release concentrations. Cypermethrin concentrations in water samples were closely correlated with dye concentrations, indicating that dye analyses were an accurate surrogate for cypermethrin concentrations. Most samples taken after the releases of azamethiphos were not toxic to test organisms in 48 h exposures and none were beyond 20 min post-release. By contrast, almost all samples taken after the release of cypermethrin, even up to 5-h post-release, were toxic. Data indicate the potential to cause toxic effects over areas of hectares from a single release of cypermethrin.

The toxicity of chlorothalonil to aquatic fauna and the impact of its operational use on a pond ecosystem.

Chlorothalonil is a fungicide whose heavy use in eastern Canada gives it the potential for significant aquatic contamination. Laboratory bioassays and field treatments of a pond system were undertaken to determine the toxic effects of chlorothalonil on aquatic fauna. The 96-h LC50 of technical chlorothalonil for rainbow trout (Oncorhynchus mykiss) was 76 micrograms/L and was not significantly different (p less than 0.05) from that of the formulated product (Bravo 500). The 96-h LC50 of Bravo 500 for blue mussels (Mytilus edulis) and clams (Mya arenaria) was 5.9 mg/L and 35.0 mg/L respectively, while its 48-h LC50 to Daphnia magna was between 130 micrograms/L and 200 micrograms/L. Chlorothalonil exposure of Daphnia to concentrations as low as 32 micrograms/L significantly (p less than 0.05) increased the time to production of first young, but there were no delayed effects on number of young produced or growth at concentrations of 180 micrograms/L or less. Chlorothalonil was initially accumulated by blue mussels to concentrations approximately ten times greater than exposure concentrations; however, tissue concentrations returned to the same level as exposure concentrations within 96 h. Spraying of ponds resulted in mortality of caged water boatmen (Sigara alternata) and threespine stickleback (Gasterosteus aculeatus) which could be related to chlorothalonil exposure, however, caddisfly larvae (Limnephilus sp.), freshwater clams (Psidium sp.), water beetles (Haliplus sp.), scud (Gamarus spp.) and midge larvae (Chironomidae) did not suffer substantial chlorothalonil-induced mortality. Changes in endemic benthic invertebrate abundance after sprays were not remarkable or related to treatment. Faunal impacts in the pond were generally of a smaller magnitude than were predicted by bioassay results.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological and morphological characteristics of periodontal mesencephalic trigeminal neurons in the cat--intra-axonal staining with HRP.

Intra-axonal recording and horseradish peroxidase (HRP) injection techniques were employed to define the response properties of periodontal mechanoreceptive afferents originating from the trigeminal mesencephalic nucleus (Vmes) and their morphological characteristics. The periodontal Vmes neurons were classified into two types: slowly adapting (SA) and fast adapting (FA) types. The central terminals of 7 SA and 4 FA afferents were recovered for detailed analyses. The whole profile of SA and FA neurons were unipolar in shape and their cell bodies were located in the dorsomedial parts of the Vmes. The united (U) fiber traveled caudally from the soma to the dorsolateral aspect of the trigeminal motor nucleus (Vmo), where it split into the peripheral (P) and C fibers with a T- or Y-shaped appearance. The P fiber joined the trigeminal sensory or motor tract. The C fiber descended caudally within Probst's tract. All 3 stem fibers issued main collaterals. The main collaterals of all neurons examined formed terminal arbors in the supratrigeminal nucleus (Vsup) and all but two SA neurons projected to the intertrigeminal region (Vint), while the projections to other nuclei of the trigeminal motor nucleus (Vmo), juxtatrigeminal region (Vjux), main sensory nucleus (Vp) and oral nucleus (Vo.r) differed between SA and FA afferents and between neurons of the same type. The SA and FA neurons were classified into three and two subgroups, respectively. The major differences in central projections between the two types were that all the FA neurons projected to the Vp or Vo.r but none of SA type and this relation was reversed in the projection to the Vjux, and that more than half of SA neurons projected to Vmo but only one FA neuron to the Vmo. The Vmes neurons which sent their collaterals into the Vmo had the P fiber passing through the tract of the trigeminal motor nerve. The average size of somata and mean diameters of U fibers and main collaterals from C fiber were significantly larger in SA neurons than FA neurons. The average size of fiber varicosities became smaller in the following nuclei, Vmo, Vsup, Vp, Vint and Vo.r, but not significant between the two functional types. The functional role of the periodontal Vmes afferents to jaw reflexes was discussed particularly with respect to their central projection sites in the brainstem nuclei.

Somatotopic organization of tooth pulp primary afferent neurons in the cat.

Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate (HRP-WGA) was used to study the somatotopic organization of pulpal afferent neurons innervating the different types of teeth in the trigeminal ganglion and trigeminal sensory nuclear complex (TSNC). In separate animals, the upper first 3 incisors (UI1-3), canine (UC), second premolar (UP2) and third premolar (UP3), and the lower first three incisors (LI1-3), canine (LC), first premolar (LP1), second premolar (LP2) and molar (LM) were traced in this experiment. Cell bodies innervating posterior teeth were found with greater frequency in dorsal maxillary ganglion regions, while somata supplying more anterior teeth were predominant ventrally. In contrast, cell bodies innervating the lower teeth were not arranged in a somatotopic fashion in the mandibular subdivision. Each pulpal afferent from lower and upper teeth projected to the subnucleus dorsalis (Vpd) of the pars principalis, the rostrodorsomedial (Vo.r) and dorsomedial parts (Vo.dm) of the pars oralis (Vo), the medial regions of the pars interpolaris (Vi), and laminae I, II, and V of the medullary dorsal horn, and terminal fields between the upper and lower teeth were separated in each subdivision. Pulpal projections from both the upper and lower teeth to each subdivision were organized in a somatotopic manner, while an extensive overlap in projections was noted between the adjoining teeth. In the Vpd, the upper and lower teeth were represented dorsoventrally, and projections from the anterior to posterior teeth in the upper jaw were arranged in both rostrocaudal and ventrodorsal sequences whereas those in the lower jaw were organized caudarostrally and lateromedially. In the Vo.r and Vo.dm, the upper and lower teeth were represented in a mediolateral sequence and projections from the anterior to posterior teeth were organized in a ventrolateral to dorsomedial sequence. In the Vi, pulpal projections were organized in a topographic fashion similar to that observed in the Vo.r and Vo.dm. In the medullary dorsal horn, the upper and lower teeth were represented in laminae I, II and V in a lateromedial sequence. Their projections to laminae I and V were topographically organized in a mediolateral and rostrocaudal sequence.(ABSTRACT TRUNCATED AT 400 WORDS)

Morphological and functional properties of trigeminal nucleus oralis neurons projecting to the trigeminal motor nucleus of the cat.

Horseradish peroxidase (HRP) was injected into the somata located in the rostrodorsomedial part (Vo.r) of the trigeminal nucleus oralis; an axonal projection to the trigeminal motor nucleus (Vmo) was demonstrated in two Vo.r neurons. The two neurons differed in their morphological and functional properties. The first Vo.r neuron responded to stimulation of low-threshold mechanoreceptors and its stem axon gave off massive axon collaterals that issued terminal branches to the dorsolateral subdivision of Vmo, Vo.r, and the medial and lateral parts of the lower brainstem reticular formation. The second Vo.r neuron was activated by stimulation of the tooth pulp or lingual nerve at twice longer latency than that of the first neuron. This stem axon was divided into two main ascending and one descending branches, and one of the main ascending branches was further bifurcated into two branches. The main non-bifurcated ascending branch gave off 4 collaterals, two of which sent terminal branches into the dorsolateral subdivision of Vmo and others into the Vo.r and juxta-trigeminal regions. The somato-dendroarchitectonic differences were also described in the two Vo.r neurons stained.

Morphology of single mesencephalic trigeminal neurons innervating periodontal ligament of the cat.

The morphology of single neurons in the trigeminal mesencephalic nucleus (Vmes) that innervate periodontal ligament was studied in cats by the method of intraaxonal injection of horseradish peroxidase (HRP). Two kinds of Vmes neurons were distinguished on the basis of differences in axon profile and its central projection. The first type of Vmes neurons was unipolar in shape and its axon was divided into united (U), peripheral (P), and central axons (C). The U axon traveled caudally within the Vmes from the soma to the dorsolateral aspect of trigeminal motor nucleus (Vmo), where it split into the P and C axons with a T-shaped appearance. The P axon joined the spinal trigeminal tract across the trigeminal principal nucleus and ran within the tract and sensory root to exit the brainstem. The C axon traveled caudally within Probst's tract. All 3 axons issued axon collaterals. Axon collaterals from the U, P and the proximal C axons sent their terminal branches into the supra (Vsup) and intertrigeminal regions (Vint). Most axon collaterals from the C axon sent their terminal branches into the juxtatrigeminal regions (Vjuxta). The second type of Vmes neurons was bipolar and issued P and C axons. The C axon ran a short distance in the Vmes to leave the Vmes, and then it traveled caudolaterally in the rostrodorsomedial aspect of the Vmo. Finally, it entered in the Vmo and traveled caudally in the dorsolateral subdivision of the nucleus to its rostrocaudal mid-level. The C axon gave off massive axon collaterals.(ABSTRACT TRUNCATED AT 250 WORDS)