true-blue and nuclear-yellow

The nasal epithelium is richly invested with peptidergic (substance P and calcitonin gene-related peptide [CGRP]) trigeminal polymodal nociceptors, which respond to numerous odorants as well as irritants. Peptidergic trigeminal sensory fibers also enter the glomerular layer of the olfactory bulb. To test whether the trigeminal fibers in the olfactory bulb are collaterals of the epithelial trigeminal fibers, we utilized dual retrograde labeling techniques in rats to identify the trigeminal ganglion cells innervating each of these territories. Nuclear Yellow was injected into the dorsal nasal epithelium, and True Blue was injected into the olfactory bulb of the same side. Following a survival period of 3-7 days, the trigeminal ganglion contained double-labeled, small (11.8 x 8.0 microm), ellipsoid ganglion cells within the ethmoid nerve region of the ganglion. Tracer injections into the spinal trigeminal complex established that these branched trigeminal ganglion cells also extended an axon into the brainstem. These results indicate that some trigeminal ganglion cells with sensory endings in the nasal epithelium also have branches reaching directly into both the olfactory bulb and the spinal trigeminal complex. These trigeminal ganglion cells are unique among primary sensory neurons in having two branches entering the central nervous system at widely distant points. Furthermore, the collateral innervation of the epithelium and bulb may provide an avenue whereby nasal irritants could affect processing of coincident olfactory stimuli.

Topics: Animals; Benzimidazoles; Benzofurans; Brain Stem; Fluorescent Dyes; Nasal Mucosa; Neurons; Olfactory Bulb; Olfactory Pathways; Rats; Rats, Sprague-Dawley; Trigeminal Ganglion; Trigeminal Nucleus, Spinal

Following injections of WGA-HRP into either the spinal cord or periaqueductal gray, labeled neurons were observed bilaterally along the periphery of the lateral reticular nucleus (LRN) magnocellular division. The possibility that some of these neurons in the LRN provide collateral axonal branches to both the periaqueductal gray and the spinal cord was investigated in rats using a retrograde double-labeling method employing two different fluorescent tracers, True Blue and Nuclear Yellow. Following sequential injection of the two fluorescent axonal tracers into the spinal cord and periaqueductal gray in the same animal, a modest number of double-labeled neurons were observed bilaterally near the medial and dorsal perimeter of the magnocellular division of the LRN. The labeled neurons were distinctly multipolar in shape and measured approximately 15-18 mu in their greatest transverse diameter. No double-labeled neurons were observed in the parvocellular or subtrigeminal divisions of the LRN. Based upon these observations, it is suggested that collaterals of the LRN-spinal pathway provide feedback information to the periaqueductal gray that might then be used to modulate the participation of the latter cell group in a variety of pain processing and cardiovascular regulatory functions.

Topics: Animals; Benzimidazoles; Benzofurans; Female; Fluorescent Dyes; Male; Periaqueductal Gray; Rats; Rats, Sprague-Dawley; Reticular Formation; Spinal Cord

Injections of the fluorescent dyes Nuclear yellow and True blue were used to determine that the dorsal column nuclei project in collateral fashion to the basilar pontine nuclei (BPN) and the ventral posterolateral nucleus of the thalamus or the BPN and the superior colliculus. Results indicated that relatively few dorsal column nuclear cells project to both the basilar pons and the superior colliculus. In contrast, many dorsal column nuclear cells that project to the BPN also give rise to collateral projections to the thalamus. Thus it is suggested that the latter dorsal column-BPN connections might at least represent in part the anatomical substrate for the electrophysiological demonstration that cerebellar granule cells can be activated at relatively short latency by peripheral tactile receptor stimulation.

Topics: Afferent Pathways; Animals; Benzimidazoles; Benzofurans; Brain Mapping; Fluorescent Dyes; Pons; Rats; Spinal Cord; Superior Colliculi; Thalamus

After transplantation of autologous sciatic nerve segments into the retina of adult hamsters for 1-2 months, retrograde labelling with horseradish peroxidase demonstrated a population of ganglion cells situated peripheral to the graft. If an additional lesion was placed between the insertion of the graft and the optic disc at the same time as transplantation, in addition to labelled cells situated peripheral to the graft, retrograde labelling with horseradish peroxidase demonstrated a population of labelled neurons located between the graft and the optic disc which was not observed in animals without the additional lesion. Since the axons of this population of cells would have to turn around away from their normal course towards the optic disc and travel for about 1.5 mm in order to grow into the graft, it suggests that the peripheral nerve graft might play an active role in attracting and/or guiding damaged ganglion cell axons to grow into it.

Topics: Animals; Benzimidazoles; Benzofurans; Cricetinae; Mesocricetus; Neuronal Plasticity; Peripheral Nerves; Retina; Staining and Labeling

After injection of true blue (TB) into the pericardial sac and nuclear yellow (NY) into the left ulnar nerve of rats, most perikarya in the left eighth cervical and first thoracic dorsal root ganglia are single-labeled with either TB or NY. However, 7.1-14.7% of the sensory perikarya from the cardiac area labeled with TB are simultaneously labeled with NY. This finding indicates that some primary sensory perikarya receive processes from both the left arm and the heart. In addition to other mechanisms that may be operative in the referral of pain of cardiac origin to the medial left arm, these results suggest that sensory neurons with dichotomizing somatic and visceral peripheral processes may also contribute to this phenomenon.

Topics: Afferent Pathways; Angina Pectoris; Animals; Benzimidazoles; Benzofurans; Female; Ganglia, Spinal; Heart Conduction System; Neurons, Afferent; Pain; Rats; Rats, Inbred Strains; Sensation; Ulnar Nerve

To test the hypothesis that axons of the basal forebrain cholinergic system collateralize to innervate widely separated areas of cortex, two distinct, retrogradely transported fluorescent dyes were injected into discrete neocortical regions of three macaques. In two monkeys, True Blue was injected into parietal cortex and Nuclear Yellow into frontal cortex; in a third monkey, placement of the dyes was reversed. Following these large (3-10 microliters total) injections, neurons single labeled with either Nuclear Yellow or True Blue were seen throughout most of the ipsilateral nucleus basalis of Meynert and nucleus of the diagonal band of Broca. Neurons projecting to either frontal or parietal cortex were most heavily concentrated in the anteromedial aspect of the basal forebrain. A small number of labeled neurons was also seen in the contralateral basal forebrain. Cells single labeled with either True Blue or Nuclear Yellow were frequently adjacent to one another, but in no case was a neuron labeled with both dyes. Thus, individual neurons of the basal forebrain complex do not appear to innervate both frontal and parietal lobes of monkeys. This finding is consistent with recent studies in rodents which suggest that basal forebrain neurons innervate relatively small, restricted cortical fields.

Topics: Animals; Benzimidazoles; Benzofurans; Female; Fluorescent Dyes; Frontal Lobe; Macaca; Macaca fascicularis; Macaca mulatta; Male; Neural Pathways; Parietal Lobe; Staining and Labeling; Substantia Innominata

Using horseradish peroxidase and fluorescent compounds as retrograde tracers, the myotopical arrangement and axon trajectories of the motoneurons innervating the supramandibular and the suprahyoidal muscles were studied in the rat. Only motoneurons ipsilateral to the injection site were labelled. In the trigeminal motor nucleus, motoneurons of the superficial masseter muscle were found laterally, of the anterior deep masseter muscle centrally, and of the temporalis muscle dorsally and medially. Motoneurons of the anterior and posterior digastric muscle were located in the accessory motor nucleus of the trigeminal and facial nerve respectively. Evidence is provided that jaw-opening muscles are innervated from a separate motor complex.

Topics: Animals; Benzimidazoles; Benzofurans; Female; Fluorescent Dyes; Horseradish Peroxidase; Masticatory Muscles; Rats; Rats, Inbred Strains; Staining and Labeling

During the early postnatal development of the rat large numbers of pyramidal tract neurons are present in layer V of the occipital cortex, but by the end of the third postnatal week the distribution of pyramidal tract neurons becomes restricted to the more rostral cortical areas. This restriction is brought about by selective collateral elimination rather than by cell death. We have found, by using retrogradely transported fluorescent dyes as either short-term or long-term markers, that occipital cortical neurons which had transiently extended pyramidal tract axons maintain subcortical axonal connections to either the superior colliculus or the pons, and, at least in the case of the corticotectal projection, that the maintained collateral is present prior to the elimination of the transient pyramidal tract collateral. Further, it appears that at no time during postnatal development do the occipital pyramidal tract neurons form either callosal or ipsilateral cortico-cortical collaterals. Thus in the early postnatal occipital cortex the neurons which project through the pyramidal tract constitute a population of cells which is separate from neurons which make cortico-cortical connections, but which largely overlaps with the population of corticotectal and corticopontine neurons.

Topics: Amidines; Animals; Benzimidazoles; Benzofurans; Cerebral Cortex; Fluorescent Dyes; Neural Pathways; Pons; Pyramidal Tracts; Rats; Rats, Inbred Strains; Superior Colliculi

The arrangement of the motoneurons innervating the supramandibular and suprahyoid muscles was studied in Wistar albino rats using two fluorescent tracers: nuclear yellow and true blue. All supramandibular motoneurons were found within the trigeminal motor nucleus; they appeared to be somatotopically arranged. The suprahyoid motoneurons were located in an accessory trigeminal-facial motor complex. No overlap of the motoneuron pools of the supramandibular and suprahyoid muscle group was observed. Only motoneurons ipsilateral to the treated muscles were labeled. It was shown that a one-to-one relationship always exists between motoneuron and muscle.

Topics: Animals; Benzimidazoles; Benzofurans; Female; Masseter Muscle; Masticatory Muscles; Mesencephalon; Microscopy, Fluorescence; Motor Neurons; Rats; Rats, Inbred Strains; Temporal Muscle; Trigeminal Nuclei

Injection of true blue into rat cerebellar cortex and nuclear yellow into either the superior cerebellar peduncle or the ventral thalamus produced double-labelled neurones in the cerebellar deep nuclei. This suggests that the nucleo-cortical projection arises from collaterals of cerebellofugal fibres. The topography of this projection, and differences in collateralization between thalamic and other cerebellofugal fibres are discussed.

Topics: Animals; Axonal Transport; Benzimidazoles; Benzofurans; Cerebellar Cortex; Cerebellar Nuclei; Efferent Pathways; Neurons; Rats; Staining and Labeling