bluuebunny/crossref_metadata_2025 huggingface dataset:
Retinal ganglion cell death during optic nerve regeneration in the frog hyla moorei
Authors: Humphrey M. F. , Beazley L. D.
Published: January 2005

In the frog Hyla moorei we have estimated there to be between approximately 450,000 and 750,000 cells in the retinal ganglion cell layer. Optic axon counts and retrograde transport of horseradish peroxidase (HRP) indicated that 72–76% of these were ganglion cells. Cells of this type were distributed as a temporally situated area centralis within a horizontal visual streak.

Cell and optic axon counts showed that there was an approximately 40% loss of ganglion cells during optic nerve regeneration. Ganglion cells appeared chromatolysed by 6–8 days after an extracranial nerve crush but there was no indication of cell death until 15 days. By this stage anterograde transport of HRP indicated that axons had reached the chiasma. Death was first seen in the area centralis, extended along the streak, and finally was observed in the periphery by 65 days; cell counts demonstrated that at this time the wave of death was almost complete. We have previously shown by electrophysiological visual mapping (Humphrey and Beazley, 1982) and confirmed in this study that visuotectal projections were retinotopically organized during regeneration. Multiunit receptive fields were initially large but progressively refined starting in nasal field (temporal retina) to restore a normal projection. The similar sequences whereby the visuotectal projection became refined and death took place in the retinal ganglion cell layer suggested that death may be related to a process of organization within the regenerating projection.

In normal animals primary visual pathways revealed by anterograde transport of HRP were essentially similar to those of Rana pipiens and R. esculenta. Regenerating axons generally remained within optic pathways. Exceptions were a retinoretinal projection which was not completely withdrawn even after 1,028 days and a direct projection to the ipsilateral tectum via an inappropriate part of the optic tract.
Freeze‐fracture study of filipin binding in photoreceptor outer segments and pigment epithelium of dystrophic and normal retinas
Authors: Caldwell Ruth B. , McLaughlin Barbara J.
Published: January 2005

We have studied sterol distribution in the retinal pigment epithelial (RPE) microvillous and outer segment disc membranes of rats with inherited retinal degeneration (RCS; RCS‐p/+) and of normal genetic controls (RCS‐rdy+, RCS‐rdy+‐p/+) by using the polyene antibiotic filipin, which binds specifically to 3‐B‐hydroxy‐sterols, and freeze‐fracture techniques. Retinas were perfusion‐fixed, incubated with filipin in the same fixative, and prepared routinely for freeze‐fracture electron microscopy. In the normal retina, the distribution of filipin binding sites on both RPE microvillous and outer segment disc membranes changes during development. Prior to outer segment elongation and the onset of phagocytosis (10 days postnatal), filipin sterol complexes are homogeneously distributed in both microvillous and outer segment membranes. With the onset of phagocytosis (2 weeks postnatal and later) filipin binding in both tissues forms a proximal‐to‐distal gradient, and binding sites decrease as distance from the cell body increases. In the normal RPE microvillous membranes, binding sites are numerous proximally and sparse on the distal tips. In the normal outer segment disc membranes, binding sites are often present on the basal discs, but are sparse on the intact apical discs prior to shedding. As the discs are cast off and engulfed by the RPE, however, filipin binding increases on both disc and phagosome membranes. In the dystrophic retina, the distribution of filipin binding sites differs from the normal. First, in the microvillous membranes, the proximal‐to‐distal gradient in filipin binding is rarely present at 2 weeks postnatal and becomes prominent only after the buildup of membranous debris has begun (3–6 weeks postnatal). Second, as the photoreceptors degenerate and the membrane debris disappears (4 months postnatal), filipin binding on the microvillous membranes becomes relatively sparse and homogeneous. Third, filipin binding on the intact disc membranes does not change with outer segment elongation, and numerous filipin binding sites are present on both apical and basal outer segment disc membranes. Fourth, large aggregates of filipin binding sites occupy the vast expanses of particlefree areas of debris membranes which accumulate between the photoreceptors and the RPE. These changes in the amount and distribution of filipin binding sites in the dystrophic retina add to the evidence that the disease process involves outer segment as well as RPE membranes and suggest that alterations in cholesterol distribution could contribute to the phagocytic defect.
Brainstem origins and projections of the cervical and abdominal vagus in the golden hamster: A horseradish peroxidase study
Authors: Miceli Mario O. , Malsbury Charles W.
Published: January 2005

Vagal afferent projections, and preganglionic parasympathetic neurones contributing to the vagus nerve in golden hamsters were traced following application of horseradish peroxidase (HRP) to the proximal end of the cervical or abdominal nerve stump. Efferents in the cervical vagus were traced to their perikarya of origin in the dorsal motor nucleus (DMN) of the vagus, the commissural gray of the cervical spinal cord, the nucleus ambiguus, the nucleus of the accessory spinal nerve (NASN), and in the ventral horn dorsolateral to the NASN. Perikarya in the NASN and the region dorsolateral to it did not contribute efferent fibres to the abdominal vagus. In the remaining cell groups, fewer labelled perikarya were labelled in the abdominal cases than in the cervical cases. Extraperikaryal labelling (presumptive terminals) in the cervical cases was seen primarily in the nucleus of the solitary tract. A modest distribution of extraperikaryal grains was also noted along the inner rim of the area postrema and the ventral border of the DMN. Anterograde labelling was sparser and had a more restricted distribution in the abdominal cases. A detailed description of brainstem pathways of vagal efferent and afferent fibres is provided, as is a comparison of the present observations with those in similar studies of other species.
Morphology of central terminations of intra‐axonally stained, large, myelinated primary afferent fibers from facial skin in the rat
Authors: Hayashi Haruhide
Published: January 2005

Horseradish peroxidase was intra‐axonally injected into functionally identified primary afferent fibers within the rat spinal trigeminal tract in order to study the morphology of their central terminations. They were physiologically determined to be large, myelinated, cutaneous primary afferents by means of electrical and mechanical stimulation of their receptive fields. Ninety‐three axons that innervated vibrissa follicles, guard hair follicles, and slowly adapting receptors were stained for distances of 4–12 mm at the levels of the main sensory nucleus, spinal trigeminal nucleus, and rostral cervical spinal cord. The collaterals of single axons from these receptors formed terminal arbors in the outer part of the spinal trigeminal nucleus rostral to and near the level of the obex (rostral type collaterals). In the rostral part of the subnucleus caudalis (Vc) they were confined to lamina V (caudalis type collaterals) and in the caudal part of Vc and in cervical segments they were confined to lamina III/IV (spinal‐dorsal‐horn‐type collaterals). There were no transitional forms between the rostral and caudalis types, but there was a transitional form between the caudalis and spinal dorsal horn types. This transitional form was distributed in laminae III/IV and V. The terminal arbors of the rostral type of collaterals formed an interrupted, rostrocaudally oriented column like those seen in the lumbar dorsal horn, but the column shifted down to lamina V near the obex, and more caudally, gradually shifted upward to lamina III. Major morphological differences were not observed among the three different functional types of collaterals with respect to the rostrocaudal distribution of collaterals, and the shape and location of collaterals. The differential laminar distribution of collateral arbors of single axons along the rostrocaudal axis distinguishes the spinal trigeminal nucleus from the spinal dorsal horn where functional types of mechanoreceptive afferents form continuous or interrupted sagittal columns of terminal arbors that do not shift dorsoventrally within segments.
Development of the spinocerebellar system in the postnatal rat
Authors: Nunes M. L. Arséanio , Sotelo C.
Published: January 2005

The distribution of Spinocerebellar projections from birth to adulthood in rats was analyzed by anterograde and retrograde tracing methods. A correlation between mossy fiber synaptogenesis and the establishment of Spinocerebellar topography was also investigated with electron microscopy.

Experiments with retrograde transport techniques indicate that the spinal axons reach the cerebellum in two successive groups: the first one, appearing prenatally, contains axons from neurons in the central cervical nucleus, Clarke's column, the sacral nucleus of Stilling, as well as from border cells. The second group, which reaches the cerebellum by P3, arises from new neurons of the same nuclear regions and from scattered cells of the spinal gray matter. The distribution and the morphological appearance of the spinal cells change between P1 and P3 and give the adult pattern by P7.

The establishment of Spinocerebellar projections occurs in four successive stages. In a first stage, spinal axons reach the cerebellum and occupy the prospective white matter of the anterior vermal lobe and of the pyramis. Later, during a “waiting” stage between P1 and P3, the spinal fibers become denser in the central white matter of both their anterior and posterior target zones but do not penetrate the gray matter. From P3 to P5 the protocolumnar stage takes place, and spinal axons invade the granular layer of the anterior lobe, where they begin to be organized in nascent sagittal columns. At the end of this stage, identifiable synaptic contacts between mossy terminals and granule cell dendrites are first observed in the anterior lobe by electon microscopy. In the pyramis, invasion of the granular layer begins only at P5. Between P5 and P7 the low intercolumnar dispersion of spinal fibers disappears and the projection roaches its fourth and final stage, characterized by a columnar organization corresponding to the adult pattern of the spinocerebellar projection.

These results indicate that (1) the adult pattern of spinocerebellar projections is attained by P7. (2) The asynchronous invasion of the gray matter in the anterior and posterior lobes may be related to the chronology of mossy fiber maturation in these regions. (3) There is a temporal correlation between the columnar organization of the spinal axons and the appearance of the earliest‐maturing mossy rosettes. However, a clear relationship between synaptogenesis and topographic organization could not be demonstrated.
Projections from the cochlear nuclei in the mustache bat, Pteronotus parnellii
Authors: Zook J. M. , Casseday J. H.
Published: January 2005

Ascending projections of the cochlear nuclei in the mustache bat were analyzed by anterograde transport of [3H]‐leucine and by retrograde transport of HRP. We were particularly interested in pathways to two parts of the system: (1) to the medial superior olive, because this nucleus is missing in most echolocating bats, but appears to be present in the mustache bat, and (2) to the intermediate and ventral nuclei of the lateral lemniscus, because these nuclei are hypertrophied and highly differentiated in all echolocating bats that we have examined. The results show a highly systematic projection from the anteroventral cochlear nucleus to all of the auditory nuclei in the brain stem. After an injection of [3H]‐leucine in the anterior and dorsal part of the anteroventral cochlear nucleus, presumably in a region sensitive to low frequencies, label is seen in the following locations: ipsilateral to the injection in the lateral part of the lateral superior olive; bilaterally in the dorsal part of the medial superior olive; contralateral to the injection in the dorsal parts of the intermediate and ventral nuclei of the lateral lemniscus; and in the anterolateral part of the central nucleus of the inferior colliculus. After an injection of [3H]‐leucine in a posterior part of the anteroventral cochlear nucleus, presumably in a region sensitive to high frequencies, labeling is in the same set of nuclei, but within each nucleus the label is now in a different location; medially in the lateral superior olive, ventrally in the medial superior olive, ventrally in each division of the ventral and intermediate nuclei of the lateral lemniscus, and medially in the central nucleus of the inferior colliculus. Projections from the entire anteroventral cochlear nucleus to the inferior colliculus are confined to the ventral two‐thirds of the central nucleus. The dorsal one‐third of the central nucleus of the inferior colliculus is the principal target of the dorsal cochlear nucleus and may be a target of the posteroventral cochlear nucleus. Both of these nuclei appear to project sparsely to the ventral parts of the inferior colliculus.

We conclude first that the bilateral input to the medial superior olive in the mustache bat is similar to the input seen in other mammals. Thus this bat has a neural structure which is associated with the analysis of binaural time differences and which usually is seen only in animals with heads large enough to create interaural time differences greater than those available to Pteronotus. Second, the projections from the anteroventral cochlear nucleus diverge to three separate targets in the lateral lemniscus: one in the intermediate nucleus and two in the ventral nucleus of the lateral lemniscus. These three target areas of the lateral lemniscus then project as three parallel pathways to the inferior colliculus.
Projection systems and terminal localization of dorsal column afferents: An autoradiographic and horseradish peroxidase study in the rat
Authors: Massopust L. C. , Hauge D. H. , Ferneding J. C. , Doubek W. G. , Taylor J. J.
Published: January 2005

Projection systems from the gracile nucleus and the cuneate nuclear complex to their terminal sites in the mesencephalon, diencephalon, and cerebellum were examined by means of anterograde autoradiography and retrograde horseradish peroxidase methods.

Three projection systems emerge from the dorsal column nuclei, decussate via internal arcuate fibers, and form the contralateral medial lemniscus (ML). At the obex, some fibers split off the ML and course dorsolaterally, forming an ascending lateral system which fits the “lemniscal adjunct channel” (LAC) concept of Graybiel ('72). The ML continues rostrally as the “main lemniscal line channel” (MLLC). At the inferior colliculus, some LAC fibers terminate in the pontine nuclei, parabrachial, dorsal reticular nuclei, and the external and ventral medial part of the central nucleus of the inferior colliculus. More rostrally at the level of the superior colliculus, terminal fields are found in the medial nucleus of the medial geniculate body, the suprageniculate, pretectal, and mesencephalic reticular nuclei, marking the end of the LAC. In the diencephalon, gracile fibers leave the MLLC and form a crescentlike terminal field along the extreme lateral border of the ventral posterior lateral nucleus (VPL) of the thalamus. Cuneate MLLC fibers terminate in a bandlike formation in the VPL medial to the gracile termination.

The third fiber system, the cuneocerebellar projection, emerges from the cuneate, the external cuneate nuclei, and the “cellular bridge” and immediately enters the ipsilateral inferior cerebellar peduncle. Upon entering the cerebellum, the major fiber component remains ipsilateral and terminates as vertical bands in vermal and paravermal lobules, and lobules I through IVa. The posterior cerebellar lobe contains terminal bands in lobules VII–IX, the copula pyramidis, and the paramedian lobule.

It is concluded that the dorsolateral fiber system conforms to Graybiel's LAC. It is more divergent and probably less modality specific, whereas the medial lemniscal system conforms to the MLLC, which is said to be modality specific, less divergent, and locked to specific sensory‐motor response characteristics.

The topography of cerebellar terminal bands indicates that there is sensory‐motor representation from all parts of the body to all parts of the cerebellum, at least in the rat.
The afferent and sympathetic components of the lumbar spinal outflow to the colon and pelvic organs in the cat. I. The hypogastric nerve
Authors: Baron R. , Jänig W. , McLachlan Elspeth M.
Published: January 2005

The cell bodies of the lumbar sensory and sympathetic pre‐ and postganglionic neurons that project to the pelvic organs in the hypogastric nerve of the cat have been labeled retrogradely with horseradish peroxidase applied to the central end of their cut axons. The numbers, segmental distribution, location, and size of these labeled somata have been determined quantitatively. Afferent and preganglionic cell bodies were located bilaterally in dorsal root ganglia and spinal cord segments L3–L5, with the maximum numbers in L4. Very few cells lay rostral to L3. Afferent cell bodies were generally very small in cross‐sectional area relative to the entire population in the dorsal root ganglia. Most of the preganglionic cell bodies lay clustered just medial to the region of the intermediolateral column and extended caudally well beyond its usual limit in the upper part of L4. These neurons were, on the average, larger than the cells of the intermediolateral column itself, with the largest cells lying in the most medial positions. Most of the post‐ganglionic somata were in the ipsilateral distal lobe of the inferior mesenteric ganglion, while some (usually < 10%) lay in accessory ganglia along the lumbar splanchnic nerves and in paravertebral ganglia L3–L5. Postganglionic somata in the inferior mesenteric ganglion were larger than both labeled and unlabeled ganglion cells in the paravertebral ganglia. From the data, it is estimated that about 1,300 afferent neurons, about 1,700 preganglionic neurons, and about 17,000 postganglionic neurons project in each hypogastric nerve in the cat.
Somatostatin‐Like immunoreactivity in neurons, nerve terminals, and fibers of the cat spinal cord
Authors: Krukoff Teresa L. , Ciriello John , Calaresu Franco R.
Published: January 2005

The distribution of somatostatin‐like immunoreactivity (SS) was studied in the spinal cord of untreated cats and of cats that had received colchicine at all levels of the cord. In the dorsal horn small (less than 15 μm in diameter), round neurons were found in Rexed laminae II and III at all levels. At all levels laminae IV‐VI contained smaller numbers of immunoreactive neurons that were medium (between 15 and 25μm in diameter) to large (greater than 25μm in diameter) in size. In addition small numbers of medium‐sized neurons were observed at the dorsal and dorsomedial borders of the gray and white matter in segments C1‐5. In the sacral cord (Sl‐3), a group of medium‐sized bipolar neurons was found in the dorsolateral funiculus. In transverse sections the processes of the neurons in these two latter groups travelled in a direction parallel to the border of the gray and white matter. In the intermediate and central gray matter, in addition to the immunoreactive neurons found in the region of the intermediolateral nucleus and nucleus intercalatus of lamina VII in segments C8 to L4 (Krukoff et al., '85a), lamina VII contained immunoreactive neurons at all levels with the largest number occurring in the thoracic cord. These neurons were medium to large in size and were generally multipolar with processes travelling in all directions. Multipolar small immunoreactive neurons were also found in the central gray region (lamina X) in the thoracic and upper lumbar cord. Finally, small numbers of neurons containing SS were found in the ventral horn of the cervical and upper thoracic cord. These multipolar neurons were medium to large in size. The distribution of nerve terminals and fibers containing SS was similar to that previously described in mice, rats, guinea pigs, and primates. Although the function of somatostatin in the spinal cord is not known, its presence in neurons with short processes suggests that it may act to modify local activity in the regions where it is found, including areas involved in sensory, visceromotor, and motor functions.
The cholinergic innervation of the rat fascia dentata: Identification of target structures on granule cells by combining choline acetyltransferase immunocytochemistry and Golgi impregnation
Authors: Frotscher Michael , Léránth Csaba
Published: January 2005

A monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine‐synthesizing enzyme, was used to study cholinergic synagses on identified (Golgi stained) granule cells in the rat fascia dentata. Choline acetyltransferase immunocytochemistry was applied to 40‐μm Vibratome sections cut perpendicular to the longitudinal axis of the hippocampus. Light microscopy revealed fine varicose ChAT‐immunoreactive axons in all layers of the fascia dentata, i.e., in the stratum moleculare, the stratum granu‐losum, and the subgranular polymorph zone. Most fibers were observed in the vicinity of granule cell bodies where they ran mainly parallel to the granular layer. Next, the immunostained Vibratome sections were sandwiched between small pieces of Parafilm and piled to form a block that was covered with agar and Golgi stained. After that, the sections were separated by cutting away the agar and removing the Parafilm. Sections containing well‐impregnated granule cells were gold‐toned (Fairén et al., '77), embedded in Araldite, and subjected to ultrathin sectioning for electron microscopy. A total of 14 gold‐toned granule cells were examined in the electron microscope for synaptic contacts with cholinergic afferents. Choline acetyltransferase‐immunoreactive axon terminals were observed that established symmetric synaptic contacts with the cell bodies and dendritic shafts of the gold‐toned identified granule cells. Two types of contact were observed on spines arising from gold‐toned granule cell dendrites. Immunoreactive terminals established asymmetric synaptic contacts with the head of small spines and symmetric contacts with the stalk of large, complex spines. The boutons forming asymmetric synaptic contacts with the cup‐shaped spine head of the complex spines were not found to be immunoreactive. Our results demonstrate that cholinergic fibers to the rat fascia dentata establish characteristic types of synaptic contact with different postsynaptic elements of granule cells, suggesting a complex function of this afferent system.
Anatomical studies on the nucleus reticularis tegmenti pontis in the pigmented rat. II. Subcortical afferents demonstrated by the retrograde transport of horseradish peroxidase
Authors: Torigoe Yasuhiro , Blanks Robert H. I. , Precht Wolfgang
Published: January 2005

The subcortical nuclear groups projecting to the nucleus reticularis tegmenti pontis (NRTP) were studied in pigmented rats with the aid of the retrograde horseradish peroxidase (HRP) technique. Small iontophoretic injections of HRP were placed in the medial regions of the NRTP, an area that has been shown in several species to be involved in eye movements. Other large injections in the NRTP or small injections placed just outside the nucleus were used to clarify the projections to the NRTP. Results indicate that the NRTP receives afferents from (1) visual relay nuclei, including the nucleus of optic tract, the superior colliculus, and the ventral lateral geniculate nucleus; (2) oculomotor‐associated structures including the zona incerta, the H1 and H2 fields of Forel, the nucleus subparafasciculus, the interstitial nucleus of Cajal, the visual tegmental relay zone of the ventral tegmental area of Tsai, the mesencephalic, pontine, and medullary reticular formations, the nucleus of the posterior commissure, and a portion of the periaqueductal gray termed the supra‐oculomotor periaqueductal gray; (3) cerebellar and pontomedullary nuclei, including the superior, lateral, and medial vestibular nuclei, the deep cerebellar nuclei, and NRTP interneurons, and (4) nuclei related to limbic functions including the lateral habenula, the mammillary nuclei, the hypothalamic nuclei, the preoptic nuclei, and the nucleus of diagonal band of Broca.

A surprisingly large number of afferents to the medial regions of the NRTP arise from visual‐ or eye‐movement‐related nuclei. The projection from the nucleus of the optic tract (NOT) confirms previous anatomical and physiological studies on the pathways involved in horizontal optokinetic nystagmus, but the number of NOT afferents is small in relation to other areas potentially related to visuomotor pathways such as the zona incerta, ventral lateral geniculate nucleus, fields of Forel, perirubral area, and subparafasciculus. The NRTP may also relay information related to vertical visuomotor reflexes (e.g., vertical optokinetic nystagmus) given the strong projections from the medial terminal nucleus of the accessory otpic system, visual tegmental relay zone, supra‐oculomotor periaqueductal gray, interstitial n. of Cajal, and midbrain reticular formation. The presence of significant NRTP projections from the superior colliculus and the mesencephalic and pontine reticular formations suggests that these nuclei may provide the pathways for the noted saccade‐related activity of NRTP neurons. In addition, projections from the vestibular nuclei were found that provide the anatomical basis for head velocity signals recorded in NRTP neurons. Lastly, the dense labeling within the deep cerebellar nuclei, most notably the dentate nucleus, confirms previous reports that the NRTP is intimately involved in the feedback control of cerebellar function.
Organization of the efferent, vestibular nuclei and nerves of the toadfish, Opsanus tau
Authors: Highstein Stephen M. , Baker Robert
Published: January 2005

The efferent vestibular nuclei and nerves were studied in the toadfish, Opsanus tau, with morphological and electrophysiological techniques. The origin and course of the efferent vestibular nerves was extensively documented. One major morphological observation was that the efferent nerves comprise a peripheral network that is anatomically distinct, and separable by dissection from the primary afferents innervated by each end organ. These anatomically distinct nerves are likely to be a major asset in physiological studies of efferent vestibular function. The retrograde transport of horseradish peroxidase (HRP) from each of the nerves innervating the vestibular and lateral line organs was used to delineate the subgroups of efferent neurons projecting to these end organs. The efferent vestibular nuclei are located in the posterior medulla in and around the median longitudinal fasiculi (MLF). We divided the nuclei cytoarchitecturally into lateral, medial, and' dorsal subdivisions. The lateral cells had bilateral dendritic trees while the dorsal cells had ipsilateral, unilateral dendritic trees. There was a higher proportion of lateral cells that innervated the canal organs and the utricle while the dorsal cells tended to innervate the other organs. The total number of cells obtained by summing those from separate nerve label was twice the total cell count present in the nuclei. Indirectly, this indicates that some cells project to more than one end organ. Efferent neurons were penetrated with glass microelectrodes, and their end organs and patterns of connectivity with other end organs were investigated by stimulating various vestibular nerves. Posterior semicircular canal efferent cells are electrically coupled to each other and could be activated electrically or chemically by stimulating other ipsilateral or contralateral vestibular nerves. It is suggested that electrical coupling might be responsible for the uniform behavior of these cells under certain conditions. Morphological and physiological experiments suggested that the semicircular canals are innervated by their own, exclusive populations of efferent neurons while other end organs may share efferent innervation. Single cells were injected intracellularly with HRP and their morphology was studied and characterized by light microscopy. Intracellular label confirmed the morphological features demonstrated by retrograde transport of HRP and also revealed that some cells had central axon collaterals that terminated within the MLF. These morphological and physiological results provide a basis for understanding the behavior of efferent vestibular neurons in the alert animal.
A new enzyme marker for striatal compartmentalization: NADPH diaphorase activity in the caudate nucleus and putamen of the cat
Authors: Sandell Julie H. , Graybiel Ann M. , Chesselet Marie‐Françcoise
Published: January 2005

The distribution of dihydronicotinamide adenine dinucleotide phosphate diaphorase (NADPH diaphorase) was studied by enzyme histochemistry in the striatum of the adult cat. Neurons and neuropil expressing NADPH diaphorase activity were found throughout, the striatum. The diaphorasepositive neurons formed a sparse population of medium‐sized cells. In the caudate nucleus they were recognized by antisera against somatostatin 14, somatostatin 28(1‐12), neuropeptide Y and avian pancreatic polypeptide. The diaphorase activity of the striatal neuropil was characterized by a modular organization that was particularly distinct in the caudate nucleus. This organization was analyzed by comparing the patterns of diaphorase staining with the distribution of acetylcholinesterase activity in adjacent sections. The NADPH diaphorase activity was found to be dense in the acetylcholinesterase‐rich matrix of the caudate nucleus, but weak in the acetylcholinesterase‐poor compartments known as striosomes.

Because of the colocalization of perikaryal NADPH diaphorase activity and somatostatinlike immunoreactivity, a comparison was also made between the distribution of diaphorase staining and immunostaining for somatostatinlike peptide in the striatal neuropil. Both observed striosomal ordering, so that the acetylcholinesterase‐poor zones detected in adjoining sections corresponded to regions of low somatostatinlike immunoreactivity as well as low NADPH diaphorase staining. In some regions striosomes were more clearly delineated in the stains for diaphorase and somatostatinlike immunoreactivity than in the acetylcholinesterase stain. These observations suggest that NADPH diaphorase may be a sensitive marker for the somatostatinergic neuropil as well as the somatostatinergic perikarya of the striatum, and that this enzyme could prove valuable in attempts to differentiate the processes of intrinsic somatostatin‐containing fibers from any extrinsic somatostatin afferents that may exist.
An ultrastructural study of interplexiform cell synapses in the human retina
Authors: Linberg Kenneth A. , Fisher Steven K.
Published: January 2005

Using serial sections and electron microscopy, we have found several morphological types of synapses within the outer plexiform layer (OPL) of the human retina. The most conspicuous of these is described in this paper. They have a unique morphology and form synapses with rod and cone bipolar cells in the OPL and onto bipolar and amacrine cell bodies in the inner, nuclear layer (INL). Because they occur in processes that extend across the INL, we believe these synapses are made by interplexiform cells (IPCs). These same processes also contact cone pedicles with specialized cell junctions like those made between cones and flat bipolars. These junctions have densification of both cell membranes and widening of the extracellular cleft, but no accumulation of synaptic vesicles. Similar‐appearing processes in the inner plexiform layer are thought to belong to IPCs but their contacts were less completely identified. Possible circuitry for these IPCs is described and the possibility that there are different classes of IPCs in the human retina is discussed.

The OPL forms in the posterior retina during the tenth fetal week. Our observations suggest that different types of synapses including those of the IPCs are present in this layer from the time of its first appearance.
Morphology and synaptic connections of myelinated primary axons in the ventrolateral region of rat trigeminal nucleus oralis
Authors: Falls William M.
Published: January 2005

Neurons in the ventrolateral (VL) subdivision of rat trigeminal nucleus oralis (Vo) have most of their dendritic arbors confined within this region. This study examines the morphology and synaptic connections of a population of myelinated primary trigeminal axons that arborize within VL and are in a position to provide input directly to VL neurons. Primary axons were visualized for light and electron microscopic analysis by injecting 30% horseradish peroxidase (HRP) in 2% dimethylsulfoxide (DMSO) into the sensory root of the trigeminal nerve and allowing 24–36 hours for the anterograde transport of HRP into the terminal axonal arbors. This population is characterized by its cone‐shaped terminal arbors, which generate many axonal endings (2–8 μm in diameter) along unmyelinated terminal strands. These arbor s arise from collaterals emanating from thinly myelinated (2–5 μm in diameter) parent branches descending in the spinal V tract, which, on the basis of their size, are considered to be small myelinated (As) primary trigeminal axons.

HRP‐labeled P endings belonging to this population of primary axons are scalloped, filled with spherical to ovoid (40–70 nm in diameter) synaptic vesicles, and lie centrally in glomeruli where they make asymmetrical axodendritic synapses on dendritic shafts and spine heads. It is at these synapses that this population of primary trigeminal axons is probably transferring its input directly to the dendritic arbors of VL neurons. The dendritic shafts and spine heads also receive symmetrical to intermediate axodendritic synapses from endings containing flattened (70 × 29 nm) synaptic vesicles. These terminals also establish axo‐axonic synapses on the P ending. Other synaptic components found less often in the glomeruli include small terminals containing oval (14–23 nm) synaptic vesicles that establish symmetrical to intermediate synapses on the P. ending, boutons containing pleomorphic (35–80 nm) synaptic vesicles that form symmetrical to intermediate synapses on the P ending as well as on dendritic shafts, and small peripheral endings containing round (20–40 nm) synaptic vesicles that establish asymmetrical synapses on dendritic shafts.
Comparative distribution of 3H‐GABA uptake and GAD immunoreactivity in goldfish retinal amacrine cells: A double‐label analysis
Authors: Yazulla Stephen , Studholme Keith , Wu Jang‐Yen
Published: January 2005

The comparative distribution of 3H‐GABA uptake and glutamic acid decarboxylase immunoreactivity (GAD‐ER) in amacrine cells of goldfish retina was studied simultaneously by using a combined autoradiographic/immunocytochemical technique in order to determine the degree of colocalization of these two markers of GABAergic neurons; 3H‐GABA was taken up most intensely by large pyriform Ab amacrine cells (3% of inner nuclear layer (INL) somata), and less intensely by smaller, polyform amacrine cells (12% of INL somata), cell bodies in the ganglion cell layer (one‐half as common as Ab cells), and cell bodies in the inner plexiform layer (very rare). GAD‐IR was observed in 25% of amacrine cells in the INL, the vast majority of which were polyform in shape, and cell bodies in the ganglion cell layer. Twice as many cells were labeled for GAD‐IR as for 3H‐GABA uptake. Of the cells that took up 3H‐GABA, colocalization of 3H‐GABA uptake and GAD‐IR was observed in 90% of the polyform amacrine cells, 80% of the cells in the ganglion cell layer, and none of the pyriform Ab amacrine cells or cells in the inner plexiform layer. We suggest that the polyform cells compose the major population of GABAergic amacrine cells in the goldfish retina, rather than the pyriform Ab cells. GABAergic displaced amacrine cells or ganglion cells are also indicated by our data. The implications of these data with regard to the physiology of the goldfish retina are discussed as well.
The sympathetic and sensory components of the caudal lumbar sympathetic trunk in the cat
Authors: Jänig W. , McLachlan Elspeth M.
Published: January 2005

The cell bodies of the lumbar sensory and sympathetic pre‐ and postganglionic neurons that project in the caudal lumbar sympathetic trunk of the cat have been labeled retrogradely with horseradish peroxidase applied to the central end of their cut axons. The application was made just proximal to the segmental ganglion that sends its gray rami to the L7 spinal nerve, and so identified the sympathetic outflow concerned primarily with the vasculature of the hindlimb and tail. The numbers, segmental distribution, location, and size of the labeled somata have been determined quantitatively. Labeled cell bodies were found ipsilaterally, but the segmental distributions of the different cell types were not matched. Afferent cell bodies lay in‐dorsal root ganglia Ll‐L5 (maximum L4), preganglionic cell bodies in spinal segments T10‐L5 (maximum L2/3), and postganglionic cell bodies in ganglia L2‐L5 (maximum L5). Both numbers and dimensions of labeled dorsal root ganglion cells were variable between experiments (maximum about 1,000); the majority were small relative to the entire population of sensory neurons. Labeled preganglionic cell bodies were located right across the intermediate region of the spinal cord, extending from the lateral part of the dorsolateral funiculus to the central canal. The highest density of labeled neurons lay at the border between the white and gray matter (corresponding to the intermediolateral cell column) with smaller proportions medially in L1‐L2, and laterally in caudal L4‐L5. Medial ‐ preganglionic neurons were generally larger than those lying in lateral positions. From the data, it is estimated that about 650 afferent, about 4,500 preganglionic, and some 2,500 postganglionic neurons project in each lumbar sympathetic trunk distal to the ganglion L5 in the cat.
The determination of dendrite morphology on lateral rectus motoneurons in cat
Authors: Russell‐Mergenthal Helen , McClung J. Ross , Goldberg S. J.
Published: January 2005

Previously developed morphometric analysis of motoneurons (Ulfhake and Kellerth, '81, J. Comp. Neurol 202: 571‐583) was applied to lateral rectus motoneurons (LRMs). Total dendrite size was approximated from a single stem dendrite measurement. Fifteen dendrites from nine LRMs of the principal abducens nucleus intracellularly stained with HRP were morphometrically analyzed. The diameters and lengths along the extent of the dendrite were measured to calculate the surface area, volume, and combined length of the process. Linear correlation of stem dendrite diameter to these size parameters produced r values of .80, .84, and .61, respectively.

Although the regression lines could be used to estimate dendrite size from the stem dendrite diameter, two morphologically distinct types were found among the 83 dendrites of the nine cells. Six dendrites differed from the other 77. Therefore, these six and a representative sample of the more common dendrite (nine) were included in the measurements. The rare dendrites consistently branched at about 40 μm from the soma into a rostrally and a caudally directed secondary dendrite. The secondary dendrites branched less and reduced more in diameter by tapering. Also, these dendrites exhibited a higher than expected total dendrite size to stem diameter ratio compared to “regular” dendrites. Statistical correlations of the stem diameter to surface area or volume within each dendrite type showed clear increases in r values from those of all 15. Significant differences were found between the size parameters of the two types. These qualitative and quantitative differences should be considered in accurate motoneuron size determinations in the abducens nucleus.
Laminar and cellular localization of cytochrome oxidase in the cat striate cortex
Authors: Kageyama Glenn H. , Wong‐Riley Margaret
Published: January 2005

Cytochrome oxidase (C.O.) was histochemically localized in the cat striate cortex at the light and electron microscopic levels. The results indicate that the oxidative metabolic activity within the cat striate cortex may vary between (1) different laminae, (2) neurons and glia, (3) different neuron types, (4) dendrite and soma of the same cell, (5) different types of dendrites, (6) different segments of the same dendrite, and (7) different classes of symmetric and asymmetric axon terminals. Maximal laminar C.O. staining was localized within geniculoreceptive layer IV. Darkly reactive neurons include the large (presumed corticotectal) pyramids of layer V, and various classes of large and medium‐sized presumed GABAergic nonpyramidal cells sparsely distributed throughout layers II–VI. The small and medium‐sized pyramids of layers II, III, V, and VI, as well as many of the smaller presumed GABAergic neurons, were only lightly or moderately reactive. The darkly reactive neurons tended to be those that received convergent or proximally localized asymmetric axosomatic synapses, implying that they are strongly driven by excitatory synaptic input. The darkly reactive nonpyramids resembled those that form GAD+, symmetric axosomatic synapses with pyramidal cells. The dark reactivity of the symmetric synaptic terminals indicates that they mediate strong inhibition of neuronal discharge. The dark reactivity of a class of large asymmetric terminals in layer N is likely to represent highly active geniculocortical terminals. The predominant distribution of elevated C.O. reactivity in dendrites is correlated with reported sites of (1) convergent excitatory synaptic input, (2) maximal field potentials, (3) highly active ion transport, and (4) Na+,K+‐ATPase.
Connections of the pigeon dorsomedial forebrain studied with WGA‐HRP and 3H‐proline
Authors: Casini Giovanni , Bingman Verner P. , Bagnoli Paola
Published: January 2005

The afferent‐efferent connections of the pigeon dorsomedial forebrain, which is composed of the “hippocampus” (Hp) and “parahippocampus” (APH), presumed homologues of the mammalian hippocampal complex, were studied. Afferent projections were identified by wheat germ agglutininconjugated horseradish peroxidase (WGA‐HRP) and efferent projections were identified by 3H‐proline and WGA‐HRP.

In addition to identified intrinsic connections within Hp and APH, both Hp and APH were found to be in receipt of ipsilateral forebrain afferents from each other, the hyperstriatum accessorium, nucleus of the diagonal band, nucleus taeniae, and area corticoidea dorsolateralis. Only Hp received input from the contralateral Hp while only APH received input from the ipsilateral hyperstriatum dorsale and archistriatum, pars ventralis. Both Hp and APH received ipsilateral diencephalic afferents from the nucleus mamillaris: lateralis, stratum cellulare internum, nucleus lateralis hypothalami, and nucleus paramedianus internus thalami. Only APH received bilateral input from the nucleus superficialis parvicellularis (this nucleus may send a small projection to Hp) and nucleus dorsolateralis anterior thalami, pars medialis, and an ipsilateral projection from the nucleus subrotundus. Brainstem afferents to Hp and APH included ipsilateral projections from the area ventralis (Tsai) nucleus reticularis pontis oralis, nucleus raphes, nucleus subceruleus dorsalis, and nucleus centralis superior of Bechterew, and bilateral projections from the nucleus linearis caudalis and locus ceruleus, of which the nucleus subceruleus dorsalis, nucleus centralis superior of Bechterew, and locus ceruleus projected to APH only.

Forebrain efferents from both Hp and APH were found to project ipsilaterally to the septum, the area of the fasciculus diagonalis Brocae, nucleus taeniae, and area corticoidea dorsolateralis. Only Hp appeared to send efferents to the contralateral septum and Hp, while only APH sent efferents to the hyperstriatum dorsale and the archistriatum. A hypothalamic projection from Hp and APH was found to partially terminate near the nucleus mamillaris lateralis. At the level of pathway connections, the results demonstrate a striking similarity between the avian dorsomedial forebrain and the dorsomedial cortex of reptiles and the mammalian hippocampus.
Morphology and physiology of the brainstem nuclei controlling the electric organ discharge in mormyrid fish
Authors: Grant K. , Bell C. C. , Clausse S. , Ravaille M.
Published: January 2005

The motoneurons to the mormyrid electric organ are driven from the medullary relay nucleus. This nucleus is in turn innervated by an adjacent cell group, nucleus C. The goals of this study were to characterize the morphology and physiology of neurons in these two nuclei, and to test the hypothesis that nucleus C is the command nucleus responsible for initiating the electric organ discharge. Medullary relay neurons and nucleus C neurons were recorded intracellularly and labeled with horseradish peroxidase.

Medullary relay neurons have a richly branched dendritic arborization, Confined mainly to the nucleus itself, and somatosomatic, dendrosomatic, and presynaptic dendro‐axonal gap junctions have been observed. Medullary relay neuron axons descend to the spinal cord without branching.

Nucleus C dendrites extend far into the ventral reticular formation. Axons of nucleus C neurons have one branch that ramifies densely within the medullary relay nucleus, forming large club endings on the medullary relay neuron soma. Two additional branches project bilaterally toward the bulbar command associated nuclei.

Both medullary relay neurons and nucleus C neurons fire a double action potential that precedes each electric organ discharge. Activity in nucleus C precedes that in the medullary relay nucleus by 100–300 μsec. Postsynaptic activity is recorded in nucleus C neurons but not in medullary relay neurons. Hyperpolarization of a single nucleus C neuron can lower the frequency of the electric organ discharge.

Both morphological and physiological data indicate that nucleus C is an integrating center where the electric organ command is initiated.
Sensory neurons supplying touch domes near the body midlines project bilaterally in the thoracic spinal cord of rats
Authors: Smith Carolyn L.
Published: January 2005

Sensory neurons that project bilaterally to laminae III‐V of the dorsal horns in the thoracic spinal cord of rats were described in a previous anatomical study. The electrophysiological experiments reported here show that these neurons innervate skin near the dorsal and ventral midlines.

Three series of experiments were undertaken: (1) the regions of skin supplied by subdivisions of thoracic nerves were mapped by recording from the subdivisions while mechanically stimulating the skin; (2) subdivisions containing the axons of contralaterally projecting sensory neurons were identified by antidromic activation from the contralateral dorsal horn; (3) the receptive fields of individual sensory neurons and dorsal horn neurons were characterized by single‐unit recording methods.

Contralaterally projecting sensory neurons had axons in subdivisions of the thoracic nerves that supply skin adjacent to the body midlines. Their receptive fields were located near the dorsal or ventral midline but did not extend onto the contralateral side of the body. Most of the neurons were slowly adapting “type I” units supplying touch domes. Dorsal horn neurons receiving input from contralateral sensory neurons had receptive fields that overlapped the dorsal or ventral midline. This bilateral representation of skin near the midlines may be important for the fusion of the sensory maps of the right and left sides of the body.