Organization of bilateral spinal projections to the lateral reticular nucleus of the rat

The present study was carried out to analyze the topography of bilateral spinal projections to the lateral reticular nucleus (LRN). We used retrograde transport of fluorescent tracers Fast Blue and Diamidino Yellow to identify spinal neurons projecting to the ipsilateral and/or contralateral LRN, as well as orthograde transport of Phaseolus vulgaris leucoagglutinin to identify the LRN areas where spinoreticular axons terminate. Orthograde labeling confirmed that bilateral spinoreticular projections coming from cervical and upper-thoracic segments terminate in the magnocellular division of LRN, while those coming from the lower-thoracic, lumbar and sacral segments end in the parvocellular division of the nucleus; only a sparse spinal input has been observed in the subtrigeminal division of LRN. Retrograde labeling showed that labeled neurons were present at all spinal levels and in particular large numbers in the cervical and lumbar enlargements. Retrogradely single-labeled cells were located, with contralateral predominance, in all segments of the spinal cord, within laminae IV, V, VI, VIII, and X, whereas in laminae III and VII labeled neurons were mainly observed ipsilaterally. Furthermore, a small fraction of double-labeled cells (7.4%) was observed throughout the spinal cord, mainly in laminae III, IV, VII and VIII.     

Lamina VII and VIII neurons of the S2 segment bilaterally projecting to the C6 segment of the spinal cord in the cat

Intracellular and extracellular recordings of antidromic action potentials were applied to invetigate neurons of the S2 segment projecting to the C6 segment of the cat spinal cord. The cell bodies were located in laminae VII and VIII of the gray matter while axons ascended in lateral funiculi. Thirty-two out of the total 45 neurons were found to project to the C6 segment bilaterally, seven ipsilaterally and six contralaterally. The axonal conduction velocities were in the 42–96 m/s range and in some neurons were significantly lower in distal parts of axons, supposing that some neurons may give off collateral branches to various segments of the spinal cord. It is discussed if the investigated neurons form a part of the propriospinal system or if their cervical projections are only collaterals of long tracts ascending to supraspinal levels. The organisation of the presented connections between spinal enlargements indicates their contribution in complex mechanisms of co-ordination of movements of the limbs.     

Projection to the lateral reticular nucleus from neurons located in C6-C7 segments of the spinal cord. An electrophysiological study in the cat.

Spinoreticular neurons projecting to the lateral reticular nucleus (LRN) were investigated electrophysiologically in the cervical enlargement of the cat spinal cord. Experiments were performed on alpha-chloralose anaesthetized animals. Antidromic action potentials were recorded extracellularly from cells located in C6 and C7 segments following stimulation of the ipsilateral LRN. The total sample included 50 neurons. Their cell bodies were found to be distributed in Rexed's laminae VI-VIII of the gray matter. Axonal conduction velocities ranged from 14.7 to 89.7 ms-1. Considerable differences between particular cases enabled two separate groups of slower and faster conduction to be distinguished. Values for these two groups were 14.7-44.3 ms-1 and 52.2-89.7 ms-1, respectively. Discrete differences with regard to the location of these groups were also pointed out. Such differentiation suggests that a proportion of axons from the slower conducting pool may be in fact collaterals of neurons that project to other brainstem centers or to lower levels of the spinal cord.     

Lumbar collaterals of neurons of the C6 segment projecting to sacral segments of the cat spinal cord

Electrophysiological investigations of neurons of the C6 segment of the spinal cord were made in α-chloralose anesthetized animals. It was established in the experiments that a part of long descending propriospinal neurons originating in the sixth cervical segment (C6) that projected to sacral segments (S1/S2) gave off collateral branches at the level of the fourth lumbar segment (L4). Several types of neurons were distinguished according to the ipsilateral, contralateral or bilateral course of axons at the thoracic level as well as their lumbar or sacral projections. The cell bodies of 58 identified neurons were distributed in Rexed's laminae VII and VIII of the gray matter. Axons descended in lateral funiculi and their conduction velocities varied from 50 to 85 m/s. The existence of collaterals to various segments of the lumbosacral enlargement indicates that the same information conveyed by long descending propriospinal neurons can reach separate motor centers controlling various muscles of the hindlimbs.     

Convergence of forelimb afferent actions on C7-Th1 propriospinal neurones bilaterally projecting to sacral segments of the cat spinal cord

Propriospinal neurones located in the cervical enlargement and projecting bilaterally to sacral segments of the spinal cord were investigated electrophysiologically in eleven deeply anaesthetized cats. Excitatory or inhibitory postsynaptic potentials from forelimb afferents were recorded following stimulation of deep radial (DR), superficial radial (SR), median (Med) and ulnar (Uln) nerves. 26 cells were recorded from C7, 22 from C8 and 3 from Th1 segments. The majority of the cells were located in the Rexed's laminae VIII and the medial part of the lamina VII. In 10 cases no afferent input from the forelimb afferents was found. In the remaining neurones effects were evoked mostly from DR (88%) and Med (63%), less often from SR (46%) and Uln (46%). Inhibitory actions were more frequent than excitatory. The highest number of IPSPs was evoked from high threshold flexor reflex afferents (FRA)--all connections were polysynaptic. However, inhibitory actions were often evoked from group I or II muscle afferents (polysynaptic or disynaptic) and, less frequently, from cutaneous afferents (mostly polysynaptic). Di- or polysynaptic IPSPs often accompanied monosynaptic EPSPs from group I or II muscle afferents. Disynaptic or polysynaptic EPSPs from muscle and cutaneous afferents were also recorded in many neurones, while polysynaptic EPSPs from FRA were observed only exceptionally. Various patterns of convergence in individual neuronal subpopulations indicate that they integrate different types of the afferent input from various muscle and cutaneous receptors of the distal forelimb. They transmit this information to motor centers controlling hind limb muscles, forming a part of the system contributing to the process of coordination of movements of fore--and hind--limbs.     

Electron Microscope Observations on the Effects of Polymixin B Sulfate on Cell Walls of Chlamydia psittaci

The effects of polymixin B sulfate on cell walls of mature elementary body (EB) and of immature developmental reticulate body (RB) of Chlamydia psittaci were investigated. When purified EB were treated with polymixin (10(4) units per ml or more) at 37 C for 60 min, about 70% of EB was found to be covered with a number of projections. Further incubation did not increase the percentage affected. The infectivity after treatment as assayed by the inclusion counting technique was reduced by 70% of the original titer. These results suggest that EB with the projections are no longer infective. The projections had obscure outlines and were 20 to 40 nm in diameter when seen in thin sections. In the negatively stained preparations, the projections were composed of aggregations of fine particles 4 to 5 nm in diameter. Treatment with sodium dodecyl sulfate at the same concentration used for cell wall isolation removed the projections completely, and the cell walls were converted to rather ragged forms apparently composed of outside and inside layers. When RB cell walls prepared from infected cells at 18 hr after infection were treated with polymixin at the same concentration, the projections having the same morphology with those seen on treated EB cell walls were observed only on the inside surface of cell wall.     

Distribution and relative proportions of neuropeptide Y- and proenkephalin-containing noradrenergic neurones in rat superior cervical ganglion: Separate projections to submaxillary lymph nodes

The distribution and relative proportions of neuropeptide Y (NPY)- and [Met]enkephalyl-Arg-Gly-Leu (ME-RGL)-containing sympathetic neurones in the rat superior cervical ganglion (SCG) and their projections to submaxillary lymph nodes (SLN) were determined by retrograde tracing and immunocytochemistry. Three subpopulations of neurones were detected in the SCG: 64% contained NPY, 30% contained ME-RGL, and 6% were immunonegative for both. Immunoreactive neurones were also present inside the external carotid nerve of the SCG. An injection of Fluoro-Gold (FG) into the left SLN retrogradely labeled a few neurones in the ipsilateral SCG. FG-labeled neurones contained tyrosine hydroxylase (TH) and were either positive for ME-RGL or for NPY. FG-labeled neurones immunostained for ME-RGL outnumbered by 4:1 FG-labeled neurones immunopositive for NPY. It is suggested that the sympathetic/peptidergic innervation to SLN may have distinct vasoregulatory and immunomodulatory functions.     

Examination of the macronuclear replication band in Euplotes eurystomus with monoclonal antibodies

A panel of eight monoclonal antibodies (MAbs) was prepared from spleen cells of mice immunized with macronuclear replication bands (RBs) isolated from Euplotes eurystomus. Antibodies were investigated with a solid phase radioimmunoassay (RIA) using either soluble chromatin from isolated RBs or from total macronuclei as antigen. The RIA showed that several MAbs recognized antigens present only in the RB or macronucleus, whereas others recognized antigens present in both structures. Specificity of the MAbs was also examined by indirect immunofluorescence. Antibody C10 recognized an antigen in the rear zone of the RB, whereas MAbs G6 and B2 appeared to stain both the forward and rear zones of the RB. Antibody A7 recognized an epitope distributed throughout the macronucleus except in the RB. Cytochemical studies with degradative enzymes suggested that antigens localized by immunofluorescence were composed of proteins. Immunoblots of SDS PAGE permitted identification of a few proteins that reacted with three of the RB-specific MAbs. Monoclonal antibodies that identify the presence or absence of reactivity of specific proteins in the RB could prove useful in the study of chromatin structure and the mechanism of chromatin replication.     

A sensory map based on velocity threshold of sensory neurones from a chordotonal organ in the tailfan of the crayfish

The central projections of sensory neurones innervating a strand chordotonal organ (CO) in the tailfan of the crayfish, Procambarus clarkii (Girard) have been investigated. The CO monitors movement of the exopodite of the tailfan relative to the endopodite. Intracellular recording and staining were used to characterise the response of the sensory neurones to applied stretches of the chordotonal organ and to reveal their morphology. Two gross morphological types of afferents were found: those that terminated in the terminal (6th) abdominal ganglion on the side ipsilateral to the sensory receptor, and those that had branches in the terminal ganglion and an intersegmental axon that ascended rostrally. Afferents responded to position, velocity and direction of imposed CO displacement. Afferents with particular physiological properties had similar morphologies in different crayfish. Irrespective of their directional responses, afferents had central projection areas dependent upon their velocity thresholds. Many afferents responded only during movement of the CO, and those with the lowest velocity thresholds (2°/s) had branches that projected most anteriorly, while those with progressively higher velocity thresholds (up to 200°/s) projected progressively more posteriorly. Afferents that responded to low velocity ramp movements and spiked tonically projected to more posterior areas of the ganglion than those that responded only to movements.Abbreviations A6SCI sixth abdominal sensory commissure I - CO chordotonal organ - DMT dorsal medial tract - G6 sixth abdominal ganglion - LDT lateral dorsal tract - MDT medial dorsal tract - MVT medial ventral tract - R1–4 nerve roots 1–4 - VLT ventral lateral tract - VMT ventral medial tract     

Projections of excitatory and inhibitory motor neurones to the circular and longitudinal muscle of the guinea pig colon

The aim of this study was to identify myenteric pathways to the circular and longitudinal muscle of the guinea pig proximal colon. To identify excitatory and inhibitory muscle motoneurones, we applied the neuronal retrograde tracer DiI onto the circular or longitudinal muscle layer and performed additional immunohistochemistry for nitric oxide synthase (NOS) and choline acetyltransferase (ChAT). On average 166 +/- 81 circular muscle motoneurones (CMMN) and 100 +/- 74 longitudinal muscle motoneurones (LMMN) were labelled by DiI tracing. Myenteric pathways innervating the muscle were either ascending (DiI-labelled neurones with oral projections) or descending (DiI-labelled neurones with anal projections). The circular muscle was preferentially innervated by ascending pathways (66.0 +/- 9.1%). Most ascending CMMN were ChAT-positive (87.2 +/- 8.5%), whereas descending CMMN were mainly NOS-positive (82.3 +/- 14.6%). Most ascending (62.2 +/- 11.1%) and descending (82.0 +/- 12.5%) CMMN had circumferential projection preferences (circumferential projections were longer than projections along the longitudinal gut axis). In contrast to the polarised projections to the circular muscle, the longitudinal muscle was equally innervated by ascending (46.2 +/- 15.1%) and descending (53.9 +/- 15.1%) neurones. Ascending and descending pathways to the longitudinal muscle consisted predominantly of ChAT-positive neurones (98.1 +/- 1.9% and 68.0 +/- 8.5%, respectively), and both pathways had prominent longitudinal projection preferences. Only 25.5% of the descending LMMN were NOS-positive. In conclusion, the circular muscle in the proximal colon is innervated by descending inhibitory (NOS-positive neurones) and ascending excitatory (ChAT-positive neurones) pathways. In contrast, the longitudinal muscle is primarily innervated by ascending and descending excitatory motoneurones, and only a small proportion of the descending pathway consisted of inhibitory motoneurones.     

Early development of the rat precerebellar system: migratory routes, selective aggregation and neuritic differentiation of the inferior olive and lateral reticular nucleus neurons. An overview

The migration, cytoarchitectonic segregation and neuritogenesis of the inferior olive (ION) and lateral reticular (LRN) neurons are described in the rat. Generated in the same primary precerebellar neuroepithelium, at embryonic days 12-13 (E12-E13) for the ION and E12-E14 for the LRN, the postmitotic cells take either the intraparenchymal (smms, for ION neurons) or the subpial migratory streams (mms, for LRN neurons and other populations, as those of the external cuneate nucleus, ECN). The ION neurons settle in their ultimate domain from E16 to E18, ipsilaterally to their proliferation side. The LRN (and ECN) neurons cross the midline at the "floor plate" (FP) level, and settle contralaterally to their birthplace between E17 and E19. In both cases, the acquisition of a mature dendritic tree is a late event when compared to the precocious axonogenesis. The FP structure may play a major role in i) attracting the axons of the precerebellar neurons, and ii) instructing these neurons whether to cross the midline or not. Thus, ultimately the FP may govern the pattern (crossed or uncrossed) of the projections of the ION and LRN to their common cerebellar target.     

Neutrophil-mediated suppression of virus replication after herpes simplex virus type 1 infection of the murine cornea.

Herpes simplex virus type 1 (HSV-1) infection of the murine cornea induces the rapid infiltration of neutrophils. We investigated whether these cells could influence virus replication. BALB/c mice treated with monoclonal antibody (MAb) RB6-8C5 experienced a profound depletion of neutrophils in the bloodstream, spleen, and cornea. In these animals, virus titers in the eye were significantly higher than those in the immunoglobulin G-treated controls at 3 days postinfection. By day 9, virus was no longer detectable in the controls, whereas titers of 10(3) to 10(6) PFU were still present in the neutrophil-depleted hosts. Furthermore, virus spread more readily to the skin and brains of MAb RB6-8C5-treated animals, rendering them significantly more susceptible to HSV-1-induced blepharitis and encephalitis. Only 25% of the treated animals survived, whereas all of the controls lived. Although MAb RB6-8C5 treatment did not alter the CD4+ T-cell, B-cell, natural killer cell, or macrophage populations, the CD8+ T-cell population was partially reduced. Therefore, the experiments were repeated in severe combined immunodeficiency mice, which lack CD8+ T cells. Again virus growth was found to be significantly elevated in the eyes, trigeminal ganglia, and brains of the MAb RB6-8C5-treated hosts. These results strongly indicate that in both immunocompetent and immunodeficient mice, neutrophils play a significant role in helping to control the replication and spread of HSV-1 after corneal infection.     

Characterization and regulation of RB6-8C5 antigen expression on murine bone marrow cells.

Murine bone marrow cells expressing the cell surface Ag RB6-8C5 were identified by fluorescence-activated cell-sorting analysis using a rat IgG mAb. The fluorescent intensity of RB6-8C5 was variable on bone marrow cells. This made it possible to separate bone marrow cells into distinct subpopulations, RB6-8C5neg, RB6-8C5lo, and RB6-8C5hi cells. Morphologic analysis of the sorted populations demonstrated that the Ag was expressed on myeloid cells. The expression of RB6-8C5 increases with granulocyte maturation, whereas expression is transient on cells in the monocytic lineage. The RB6-8C5hi sorted cells were enriched for end-stage neutrophils (75%), whereas the RB6-8C5lo sorted cells contained more immature myeloid cells and myelocytes (75%). Lymphocytes and macrophages were less than 5% in any RB6-8C5+ population, whereas the erythroid precursors were RB6-8C5neg. The colony forming unit culture (CFU-C) (greater than 90%) were found in the RB6-8C5neg and RB6-8C5lo populations, and all the CFU-granulocyte, erythroid, megakaryocyte, and macrophage (CFU-GEMM) and burst-forming units-erythroid (BFU-E) were in the RB6-8C5neg population. Granulocyte-macrophage-CSFR (GM-CSFR) and IL-1 alpha R were expressed on RB6-8C5hi bone marrow cells, whereas no receptors could be detected on RB6-8C5neg and RB6-8C5lo cells. The expression of the RB6-8C5 Ag can be induced on RB6-8C5neg cells in liquid culture by IL-3 and granulocyte-macrophage CSF. Thus, RB6-8C5 is a myeloid differentiation Ag whose expression can be regulated by cytokines.     

Octopamine-like immunoreactive neurones in locust genital abdominal ganglia

Using a well characterized anti-serum, the distribution of octopamine-like immunoreactive neurones is described in the locust seventh abdominal (A7) and terminal ganglia (TG), which are associated with genital organs. Apart from 4 paired ventral somata occasionally observed in the TG, all labelled cells could be identified as efferent dorsal- and ventral unpaired median (DUM/VUM) neurones by virtue of the characteristic large size and position of their somata, projections of their primary neurites in DUM-cell tracts, and bifurcating axons which arise from dorsal T-junctions and enter peripheral nerves. For the examined ganglia our data indicate that the whole population of efferent DUM and VUM-cells, defined here as progeny of the segment specific unpaired median neuroblast with peripheral axons, are octopaminergic, and that equal numbers of these cells occur in both sexes: 8 in A7 and 11 in TG. Sex-specific differences are probably restricted to the axonal projections of 5 octopamine-like immunoreactive DUM-somata in A7, and 5 in TG, which in females project into their segment specific sternal nerves, but in males into the genital nerve of the TG. Numerous intersegmentally projecting octopamine-like immunoreactive fibres traverse both ganglia. The majority probably stem from previously described octopamine-like immunoreactive neurones in the thoracic and suboesophageal ganglia.     

Neural cell surface differentiation antigen gp130(RB13-6) induces fibroblasts and glioma cells to express astroglial proteins and invasive properties.

Transient expression of the differentiation and tumor cell surface antigen gp130(RB13-6) characterizes a subset of rat glial progenitor cells susceptible to ethylnitrosourea-induced neurooncogenesis. gp130(RB13-6) is as a member of an emerging protein family of ecto-phosphodiesterases/nucleotide pyrophosphatases that includes PC-1 and the tumor cell motility factor autotaxin. We have investigated the potential role of gp130(RB13-6) in glial differentiation by transfection of three cell lines of different origin that do not express endogenous gp130(RB13-6) (NIH-3T3 mouse fibroblasts; C6 and BT7Ca rat glioma cells) with the cDNA encoding gp130(RB13-6). The effect of gp130(RB13-6) expression was analyzed in terms of overall cell morphology, the expression of glial cell-specific marker proteins, and invasiveness. Transfectant sublines, consisting of 100% gp130(RB13-6)-positive cells, exhibited an altered, bipolar morphology. Fascicular aggregates of fibroblastoid cells subsequently developed into mesh-like patterns. Contrary to the parental NIH-3T3 and BT7Ca cells, the transfectant cells invaded into collagen type I. As shown by immunofluorescence staining of the transfectant sublines as well as of primary cultures composed of gp130(RB13-6)-positive and -negative cells, expression of gp130(RB13-6) induced coexpression of proteins typical for glial cells and their precursors, i.e., glial fibrillary acidic protein, the low affinity nerve growth factor receptor, and the neural proteins Thy-1, Ran-2, and S-100. In accordance with its expression in the immature rat nervous system, gp130(RB13-6) may thus have a significant role in the glial differentiation program and its subversion in neurooncogenesis.     

Ponto-medullary projections to the spinal cord: a quantitative study in the cat

The purpose of this research has been to study quantitatively the ponto-medullary projections to the lateral and ventral funiculi in both cervical (C3) and thoracic (Th8) levels. The method consisted in the partial interruption of the spinal cord, sparing one funiculus in which 5-30 microliter of HRP 30% solution was injected at about 1 cm caudally. 19 cats were utilized, 12 for cervical (6 for lateral and 6 for ventral funiculus) and 7 for lumbar injection (3 for lateral and 4 for ventral funiculus). The structures which project to both funiculi of spinal cord (RM, RL, Poo, PR at Th8 level; RM, RL, Poo at C3 level) could exert integrative effects on the proximal and distal segments of the limbs. The structures which project only to FV (VL and Poc at Th8 level; VL, VIN and Poc at C3 level) or to FL (LSC at Th8; PR at C3) could be implied in motor control of only the proximal or distal regions.     

Microglia and astrocytes may participate in the shaping of visual callosal projections during postnatal development.

In the adult cat, axons running through the corpus callosum interconnect the border between the visual cortical areas 17 and 18 (A17 and A18) of both hemispheres. This specific pattern emerges during postnatal development, under normal viewing conditions (NR), from the elimination of initially exuberant callosal projections. In contrast, if the postnatal visual experience is monocular from birth (MD), juvenile callosal projections are stabilised throughout A17 and A18. The present study aimed at using such a model in vivo to find indications of a contribution of glial cells in the shaping of projections in the developing CNS through interactions with neurones, both in normal and pathological conditions. As a first stage, the distribution and the morphology of microglial cells and astrocytes were investigated from 2 weeks to adulthood. Microglial cells, stained with isolectin-B4, were clustered in the white matter below A17 and A18. Until one month, these clustered cells displayed an ameboid morphology in NR group, while they were more ramified in MD animals. Their phenotype thus depends on the postnatal visual experience, which indicates that microglial cells may interact with axons of visual neurones. It also suggests that they may differentially contribute to the elimination and the stabilisation of juvenile exuberant callosal fibres in NR and MD animals respectively. Beyond one month, microglial cells were very ramified in both experimental groups. Astrocytes were labelled with a GFAP-antibody. The distributions of connexins 43 (Cx43) and 30 (Cx30), the main proteic components of gap junction channels in astrocytes, were also investigated using specific antibodies. Both in NR and MD groups, until 1 month, GFAP-positive astrocytes and Cx43 were mainly localised within the subcortical white matter. Then GFAP, Cx43 and Cx30 stainings progressively appeared within the cortex, throughout A17 and A18 but with a differential laminar expression according to the age. Thus, the distributions of both astrocytes and connexins changed with age; however, the monocular occlusion had no visible effect. This suggests that astrocytes may contribute to the postnatal development of neuronal projections to the primary visual cortex, including visual callosal projections.     

Prevention of lethal experimental infection of C57BL/6 mice by vaccination with Brucella abortus strain RB51 expressing Neospora caninum antigens

Bovine abortions caused by the intracellular protozoal parasite Neospora caninum are a major concern to cattle industries worldwide. A strong Th1 immune response is required for protection against N. caninum. Brucella abortus strain RB51 is currently used as a live, attenuated vaccine against bovine brucellosis. Strain RB51 can also be used as an expression vector for heterologous protein expression. In this study, putative protective antigens of N. caninum MIC1, MIC3, GRA2, GRA6 and SRS2, were expressed individually in B. abortus strain RB51. The ability of each of the recombinant RB51 strains to induce N. caninum-specific immunity was assessed in C57BL/6 mice. Mice were immunised by two i.p. inoculations, 4 weeks apart. Five weeks after the second immunisation, spleen cells from the vaccinated mice secreted high levels of IFN-gamma and IL-10 upon in vitro stimulation with N. caninum whole cell lysate antigens. N. caninum-specific antibodies of both IgG1 and IgG2a subtypes were detected in the serum of the vaccinated mice. Mice in the vaccinated and control groups were challenged with 2 x 10(7)N. caninum tachyzoites i.p. and observed for 28 days after vaccination. All unvaccinated control mice died within 7 days. Mice in the MIC1 and GRA6 vaccine groups were completely protected while the mice in the SRS2, GRA2 and MIC3 vaccinated groups were partially protected and experienced 10-50% mortality. The non-recombinant RB51 vector control group experienced an average protection of 69%. These results suggest that expression of protective antigens of N. caninum in B. abortus strain RB51 is a novel approach towards the development of a multivalent vaccine against brucellosis and neosporosis.     

Neuronal subpopulations in autonomic ganglia associated with the chicken ureter: an immunohistochemical study

The neurochemical coding of neurones located in ganglia of the nerve trunk accompanying the chicken ureter was analysed and quantified using NADPH-diaphorase reactivity and immunohistochemistry against tyrosine hydroxylase (TH), nitric oxide synthase (NOS), calbindin (CAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and calcitonin gene-related peptide (CGRP) in untreated or colchicine-treated preparation. Almost all neurones were either positive for TH (38%) or for SOM (60%). Only 4% of the neurones were both TH- and SOM-positive and 3% of the neurones exhibited neither TH nor SOM immunoreactivity. The relative numbers of NPY-, NOS-, CAL- and VIP-positive neurones were 57%, 28%, 14% and 7%, respectively. No SP- or CGRP-positive neurones were observed. All NADPH-diaphorase-positive neurones expressed NOS immunoreactivity. Only in some TH-positive neurones was NPY and/or NOS found. Four major subpopulations were found in the ureteric ganglia. The SOM-positive neurones were subdivided into SOM/NPY/NOS- (28% of all neurones), SOM/NPY- (18%) and SOM/CAL/NPY-positive neurones (14%). A subpopulation of these peptid- ergic neurones also contained VIP. About 35% of the neurones contained TH only. Neurones of all subpopulations (72% of the neurones), except most of the CAL-positive neurones, were encircled by dense plexus of varicose SP/CGRP-positive, presumably sensory nerve fibres. Dense plexus of VIP-positive fibres were observed around 89% of the neurones. The chemical coding of the neuronal subpopulations identified in the ganglia accompanying the chicken ureter resembled that observed in the ganglia of Remak’s nerve but was remarkably different from that of the autonomic neurones described in mammalian species.