bluuebunny/crossref_metadata_2025_split huggingface dataset:
The trajectory of mitral cell axons in the rabbit olfactory cortex revealed by intracellular HRP injection
Authors: Ojima Hisayuki , Mori Kensaku , Kishi Kiyoshi 
Published: January 2005

AbstractThe projection of the axon and axon collaterals of mitral cells to the olfactory cortex was studied in the rabbit by intracellular staining with horseradish peroxidase (HRP). The stained mitral cell axons were reconstructed from the soma to the most caudal portion of the anterior piriform cortex (aPC). Single mitral cells projected to cytoarchitectonically different areas of the olfactory cortex, i.e., the anterior olfactory nucleus (AON), and the aPC, the olfactory tubercle (OT). All the stained mitrall cells projected to both the AON and the aPC, and about one‐fourth of the mitral cells projected to the OT. At the surface of the AON and the aPC, the main axon running in the lateral olfactory tract (LOT) gave off several thin collaterals at various intervals. The collaterals did not project evenly in each area but typically formed patchy terminal arbors which tended to be elongated anteroposteriorly. In both the AON and the aPC, each single mitral cell formed several terminal arbors in layer Ia. The axon collaterals innervating the OT showed two types of projection patterns. One type of collateral was emitted from the main axon within the olfactory bulb, coursed through the ventromedial portion of the olfactory peduncle without joining the main mass of the LOT and terminated mainly in the medial portion of the OT. The other type of collateral emerged from the main axon in the LOT, coursed medioposteriorly, and projected to the lateral portion of the OT.Although individual mitral cells projected to several parts of the olfactory cortex, the fact that they made dense terminal arbors in specific places in each area suggests that the bulbocortical connections are not diffuse but highly selective.
The neuronal endoplasmic reticulum: Its cytochemistry and contribution to the endomembrane system. II. Axons and terminals
Authors: Broadwell Richard D. , Cataldo Anne M. 
Published: January 2005

AbstractThe morphology and cytochemistry of the endoplasmic reticulum (ER) in axons and terminals of a number of different types of neurons in brains from mice were investigated ultrastructurally. The neurohypophysis received particular attention because the morphology and enzyme cytochemical activities of many of the preterminal swellings of hypothalamoneurohypophysial axons are altered by chronic salt‐stress. Membrane contrast and enzyme cytochemical staining techniques were employed to characterize the axonal reticulum and to determine if organelles representing the lysosomal system in the axon and the tubular profiles participating in the anterograde axonal transport of native horseradish peroxidase (HRP) are associated with the ER. Potential enzyme cytochemical markers for the axonal ER included glucose‐6‐phosphatase (G6Pase), thiamine pyrophosphatase, nucleoside diphosphatase, and acid hydroxylase activities. The anterograde transport of HRP was analyzed in undamaged hypothalamoneurohypophysial neurons and in facial and hypoglossal motoneurons of mice receiving the protein in the lateral cerebral ventricle.The ER pervaded the axon and appeared as parallel, 20–40‐nm‐wide tubules interconnected by oblique anastomoses. Membrane thickness of the axonl reticulum measured 60–100 Å, which is similar to that of the perikaryal ER. Enzyme cytochemical activities associated with the ER or lysosomes were not conspicuous in axons and terminals under normal conditions but became prominent in some axons and preterminal swellings manifesting an autophagic appearance within neurohypophyses from salt‐stressed mice. Only G6Pase activity was a marker for the ER in these axons and preterminals. Many ER profiles in non‐incubated sections and in G6Pase cytochemical preparations of salt‐stressed neurohypophyses were wrapped around or interspersed among secretory granules, multilamellar bodies, and vacuoles that may represent forms of lysosomes involved in autophagy and crinophagy. Acid hydrolase activities were localized within the vacuoles as well as within 80–130‐nm‐wide, blunt‐ended tubules in pituitary stalk axons; similar reactive tubules were confluent with large secondary lysosomes in neurosecretory cell bodies and may be derived from these lysosomes. Morphologically identical tubules transporting HRP in the anterograde direction were observed only in the salt‐stressed hypothalamo‐neurohypophysial neuron. The HRP‐positive tubules very likely are affiliated with the lysosomal system.
Uptake of 3H‐glycine in the outer plexiform layer of the retina of the toad Bufo marinus
Authors: Kleinschmidt Jochen , Yazulla Stephen 
Published: January 2005

AbstractThe uptake of 3H‐glycine in the retina of the toad, Bufo marinus, was investigated by light and electron microscopical autoradiography. Uptake of 3H‐glycine was very prominent in large cell bodies in the inner nuclear layer as well as in discrete clusters in both the outer plexiform layer (OPL) and the inner plexiform layer. This pattern is similar to that described for 3H‐glycine‐aecumulating putative interplexiform cells in goldfish, frog, and Xenopus retinas. Electron microscopical autoradiography of the OPL revealed large, grain‐containing varicosities which had electron‐lucent cytoplasm and contained both small, agranular and large, dense‐core vesicles. The varicosities made extensive en passant and spine synapses in the OPL. Definitive identification of their postsynaptic targets was not achieved. However, autoradiographic analysis with 3H‐GABA uptake as well as electrophysiological evidence suggests that axons but not cell bodies or dendrites of 3H‐GABA‐accumulating horizontal cells (H1 cells) are postsynaptic targets of the varicosities. The presence of dense‐core vesicles in the varicosities suggested co‐occurrence of glycine and a biogenic amine or neuropeptide. The indirect immunofluorescence technique was used to determine whether any such substances were present in the OPL of the toad retina. However, no specific labeling was found in the OPL for any of 19 substances tested. The extensive synaptic output provided by glycine‐accumulating varicosities in the toad OPL may indicate an important role of glycine in the synaptic function of the distal toad retina. We suggest that these varicosities derive from a presumably glycinergic interplexiform cell.
Gangliosides stimulate protein synthesis, growth, and axon number of regenerating limb buds
Authors: Maier C. Eberhardt , Singer Marcus 
Published: January 2005

AbstractWhen a newt limb is amputated and begins to regrow, regenerating axons exert a neurotrophic influence on the limb regeneration process. Previous studies have shown that direct manipulation of limb nerves, by electrical stimulation or a conditioning lesion, elevates protein synthesis, increases neurotization and accelerates growth of the limb bud. Since exogenously supplied gangliosides accelerate axonal sprouting in regenerating nerves, we wanted to know whether gangliosides would similarly affect limb regeneration. To test this, regrowing limb buds were either infused with or immersed into gangliosides, or animals were injected intraperitoneally with gangliosides. Infused gangliosides elevated protein synthesis in limb buds 15% and increased the number of axons in limb buds 45% by 6 hours after infusion. Regenerating limb bud morphogenesis was initiated 3–4 days earlier in animals receiving i.p. injections of gangliosides every 12 hours. Similarly, limbs immersed daily in gangliosides began regrowth sooner than contralateral controls and this advantage was maintained throughout the period of observation. These findings indicate that treatment with gangliosides has a salutary effect on limb regeneration.
A comparative study of neck muscle motor neurons in a cricket and a locust
Authors: Honegger Hans‐Willi , Altman Jennifer S. , Kien Jenny , Müller‐Tautz Rosemarie , Pollerberg Elisabeth 
Published: January 2005

AbstractThe gross morphology of the neck muscles of a cricket (Gryllus campestris) and their innervation are described and compared with a locust (Schistocerca gregaria) (Figs. 1,2). The motor neurons innervating the neck muscles were stained in crickets and locusts with cobalt chloride introduced via the nerve endings in the muscle. The two species show overall similarities, not only in position of the neck motor neurons in suboesophageal, prothoracic, and mesothoracic ganglia (Table 1) but also in motor neuron morphology (Figs. 4–12). However, muscle 60 in the cricket is innervated by a unique motor neuron with its axon in prothoracic nerve 3, instead of sharing motor neurons in suboesophageal nerve 8 and mesothoracic nerve 1 with muscle 59, as in locust. Muscle 62 has the same attachments and innervation with similar motor neurons in cricket and locust but a different mechanical function in the two species. The findings are discussed with respect to possible segmental homologies and to the origins of the muscles as either dorso‐ventral or longitudinal. As several muscles share the same motor neurons, we suggest that neck muscle function be described in terms of “behavioural units of action”.
Regional specializations in the eye of Aplysia, a neuronal circadian oscillator
Authors: Herman K. G. , Strumwasser F. 
Published: January 2005

AbstractThe eye of the opisthobranch mollusc, Aplysia californica, contains a neuronal circadian oscillator system as well as a photoreceptor system. The retina contains five classes of receptors, several of which are described for the first time in this paper, and two types of neurons. The most conspicuous photoreceptor has long microvilli and is densely packed with small vesicles. The other four receptor types bear both microvilli and cilia and lack densely packed vesicles. Because of their small size, these four receptors occupy only a small fraction of the retinal area, but numerically they account for about half of the receptors. There are marked differences between the dorsal and ventral portions of the eye of Aplysia. The optic nerve head and associated bundles of axons within the retina form a boundary between two anatomically distinct regions of the eye. The microvillous photoreceptor and one of the receptors bearing both microvilli and cilia are found throughout the eye. The other three receptor types are restricted to the region ventral to the optic nerve head. One type of neuron, which has been shown in other studies to produce compound action potentials whose frequency varies with a circadian rhythm, is also found only ventral to the optic nerve head and associated axon bundles. There are also marked regional variations in cellular dimensions. The rhabdom originating from the microvillous photoreceptors is thickest in the dorsal and central retina, and the cross‐sectional areas of these photoreceptors are largest dorsally. The pigmented layer is also much thicker in the dorsal retina. No other molluscan eye has been reported to have as many receptor types as Aplysia, nor has restriction of a receptor or neuronal type to a limited area been described. Regional variations in cellular dimensions have been reported previously primarily in the advanced cephalopod eyes. The significance of these unusual features is discussed in relation to both the visual properties of the eye and the circadian oscillator it contains.
A laminar analysis of the number of round‐asymmetrical and flat‐symmetrical synapses on spines, dendritic trunks, and cell bodies in area 17 of the cat
Authors: Beaulieu Clermont , Colonnier Marc 
Published: January 2005

AbstractThe number of synapses per unit volume of tissue (Nv) has been estimated in individual laminae of the binocular and monocular regions of area 17 in six adult cats by using a method of size‐frequency distribution. Separate estimates were obtained for RA synapses (containing round vesicles associated with asymmetric membrane differentiations) and for FS synapses (containing flat vesicles associated with symmetric membrane differentiations). For the total cortical thickness, the Nv of all synapses is not statistically different between binocular (286 million per mml3) and monocular (281 million) regions, nor is it different between the two regions for any of the laminae. Eighty‐four percent of synapses are of the RA type. of those, 79% are found on dendritic spines, 21% on dendritic trunks, 0.1% on somata. FS synapses represent 16% of the total, with 31% of them on spines, 62% on dendritic trunks, and 7% on somata. The ratio of RA to FS synapses is kept relatively constant throughout the layers. A two‐way analysis of variance shows no difference in the Nv of either RA or FS synapses in the two regions nor in the Nv of RA synapses between cats. It does, however, clearly demonstrate (p < 0.001) interindividual differences for FS synapses. These variations between individual cats may be due to differences in age, breed, or environmental factors. In contrast to the relative uniformity of the Nv of synapses between regions, the number of each type under 1 mm2 of cortical surface is 33% higher in the binocular region. This is due mainly to the greater thickness of the binocular region.
Anatomy of brain alpha1‐adrenergic receptors: In vitro autoradiography with [125I]‐heat
Authors: Jones Leslie Sargent , Gauger Lisa L. , Davis James N. 
Published: January 2005

AbstractMuch useful information on the localization of alpha1‐adrenergic binding sites has been gained by using tritiated radioligands for in vitro autoradiography. However, the iodinated alpha1‐adrenergic antagonist HEAT (([2‐β (4‐hydroxyphenyl)‐ethylaminomethyl)‐tetralone], BE 2254), a radioligand with high affinity and specificity, provides autoradiographs with a higher signal to noise ratio. This has allowed us to describe the anatomy of these binding sites in much greater detail than previously possible.Regions showing the highest levels of binding include external plexiform layer of the olfactory bulb, layers Va and Vc of frontoparietal cortex, lateral and central amygdaloid nuclei, thalamus, and inferior olive. Other regions were generally less intensely labeled, with the least evidence of labeling in white matter, such as corpus callosum. Some regions (e.g., hippocampus) had only moderate labeling, but the binding appeared in a discrete pattern that reflected the functional organization of the structure.Although the [125I]‐HEAT binding sites were distributed in a pattern similar to that previously reported for [3H]‐WB 4101 and [3H]‐prazosin, the anatomical detail seen with the iodinated ligand is greater. As a result, an association of alpha1‐adrenergic antagonist binding sites with specific layers in the cortex and with some catecholamine‐containing nuclei in the brainstem, such as the locus coeruleus, have been seen for the first time.
Afferent influences on brain stem auditory nuclei of the chicken: Neuron number and size following cochlea removal
Authors: Born Donald E. , Rubel Edwin W. 
Published: January 2005

AbstractThe consequences of cochlea removal on neuron number and soma cross‐sectional area were examined in the second order auditory nucleus (n. magnocellularis) of chickens. Both the age of the subjects at the time of cochlea (basilar papilla) removal (1–66 weeks) and the survival period (1–45 days) were varied. Neuron number and soma cross‐sectional area were determined from Nissl stained sections. Additional material was processed to examine the relationship of ganglion cell loss to changes in n. magnocellularis.Neuron number decreased by 25–30% and soma cross‐sectional area decreased by 10–20% ipsilateral to the cochlea removal in chickens operated on during the first 6 weeks after hatching. In contrast, in chickens operated on at 66 weeks posthatch neuron number decreased less than 10% and there was no change in soma area. The changes were rapid, being nearly complete 2 days after cochlea removal. An initial change (1 and 2 days after surgery) observed in animals operated on up to 6 weeks posthatch was the presence of a large number of neurons in which no Nissl substance could be detected. These results demonstrate an age‐dependent change in the susceptibility of NM neurons to deafferentation. This change is not temporally related to other measures of functional maturation of the auditory system.
Autoradiographic localization of estrogen and androgen receptors in the sexually dimorphic area and other regions of the gerbil brain
Authors: Commins Deborah , Yahr Pauline 
Published: January 2005

AbstractAutoradiography was used to localize sex hormone‐accumulating cells in the gerbil brain. Some areas had a high density of both androgen and estrogen receptors. These areas included the lateral septum, the bed nucleus of the stria terminalis, the medial and cortical amygdaloid nuclei, the medial preoptic area (MPOA), the arcuate nucleus, the ventromedial hypothalamus, and the periventricular central gray. This distribution of hormone receptors agrees closely with that seen in other mammals. In contrast to what has been reported for other species, the distribution of estradiol‐accumulating cells in the gerbil MPOA is different in males and females. Estradiol uptake in the posterior MPOA followed the morphology of a sexually dimorphic area (SDA) and was therefore sexually dimorphic. Moreover, the percentage of SDA cells that accumulated estradiol appeared to be higher in males than in females. The pattern of androgen accumulation also followed the morphology of the SDA but differed from the pattern of estrogen accumulation in one way. The uptake of 5α‐dihydrotestosterone in the SDA pars compacta (pc), a component of the SDA, was much greater than in the rest of the SDA. This was not true for estradiol. Since most females lack the SDApc, androgen uptake in the gerbil SDA may also be sexually dimorphic. Androgen uptake was more widespread than estrogen uptake in the brainstem. Brainstem nuclei that accumulated 5α‐dihydrotestosterone included the locus ceruleus, the dorsal raphe, the hypoglossal nucleus, the area postrema, the nucleus of the solitary tract, and the dorsal nucleus of the vagus.
Sensory innervation of periodontal ligament of rat molars consists of unencapsulated Ruffini‐like mechanoreceptors and free nerve endings
Authors: Byers Margaret R. 
Published: January 2005

AbstractThe trigeminal ganglion (TG) of adult rats was injected with 3H‐amino acids to label periodontal receptors by axonal transport; 20–24 hours after injection, samples of molar ligament were prepared for autoradiography and electron microscopy. Four types of neurites labeled from TG were found in the avascular ligament fiber regions: (1) large, complex, Ruffini‐like endings, lacking a capsule, but with finger extensions touching ligament collagen; (2) smaller Ruffini‐like endings, lacking a capsule and neural fingers; (3) free bundles of unmyelinated axons; and (4) free, small, myelinated axons. The vascular channels plus associated loose connective tissue that perforate the ligament contained labeled preterminal ensheathed axons, small Ruffini endings, and free unmyelinated or small myelinated axons. The incidence of labeled endings was about 5 × greater next to the lower third of the root than in the upper two‐thirds or beneath the root The TG myelinated axons (diameter range 2–15 μm) entered the ligament in sheathed nerve bundles; these branched to form numerous small preterminal axons that were surrounded by a periaxonal fluid space and a perineurial sheath. Terminal axons branched from nodes of Ranvier, left the preterminal chamber, and followed an extended branching course through the collagen fibers. Large, complex Ruffini‐like endings had numerous mitochondria and were partially covered by special lamellar Schwann cells and complex basal lamina; vesicles and multivesicular bodies were found near exposed regions of the receptor. Smaller Ruffini‐like endings lacked neural fingers and had a simpler structure and less elaborate Schwann cells. The structure of Ruffini‐like endings was highly varied; thus a structural continuum may exist from the largest, most complex to the smallest, simplest Ruffini‐like receptor. The TG unmyelinated axons entered the ligament in ensheathed bundles; they then branched into free bundles that were found in the avascular ligament or near blood vessels. No encapsulated receptors were found.
Reflex connections of the facial and vagal gustatory systems in the brainstem of the bullhead catfish, Ictalurus nebulosus
Authors: Morita Yasuhiro , Finger Thomas E. 
Published: January 2005

AbstractThe primary gustatory sensory nuclei in catfish are grossly divisible into a vagal lobe and a facial lobe. In this study, the reflex connections of each gustatory lobe were determined with horseradish peroxidase (HRP) tracing methods. In addition, in order to determine the loci and morphology of the other brainstem cranial nerve nuclei, HRP was applied to the trigeminal, facial, glossopharyngeal, or vagus nerve.The sensory fibers of the facial nerve terminate in the facial lobe. The facial lobe projects bilaterally to the posterior thalamic nucleus, superior secondary gustatory nucleus, and medial reticular formation of the rostral medulla. The facial lobe has reciprocal connections with the lobobulbaris, medial reticular formation of the rostral medulla, descending trigeminal nucleus, medial and lateral funicular nuclei, and the vagal lobe, ipsilaterally; and with the facial lobe contralaterally. In addition, the facial lobe receives inputs from the raphe nuclei, from a pretectal nucleus, and from perilemniscal neurons located immediately adjacent to the ascending gustatory lemniscal tract at the level of the trigeminal motor nucleus.The gustatory fibers of the vagus nerve terminate in the vagal lobe, while the general visceral sensory fibers terminate in a distinct general visceral nucleus. The vagal lobe projects ipsilaterally to the superior secondary gustatory nucleus, lateral reticular formation, and n. ambiguus; and bilaterally to the commissural nucleus of Cajal. The vagal lobe has reciprocal connections with the ipsilateral lobobulbar nucleus and facial lobe, In addition, the vagal lobe receives input from neurons of the medullary reticular formation and perilemniscal neurons of the pontine tegmentum.In summary, the facial gustatory system has connections consonant with its role as an exteroceptive system which works in correlation with trigeminal and spinal afferent systems. In contrast, the vagal gustatory system has connections (e.g., with the n. ambiguus) more appropriate to a system involved in control of swallowing. These differences in central connectivity mirror the reports on behavioral dissociation of the facial and vagal gustatory systems.
Innervation of the complexus (“hatching”) muscle of the chick
Authors: Gross Gayle H. 
Published: January 2005

AbstractThe complexus muscle of avians, also known as the “hatching” muscle, is notable for the dramatic, transient pseudohypertrophy which it undergoes around the time of hatching. The muscle is believed to be involved in specific dorsal and lateral head movements used for hatching. Innervation of the complexus muscle was studied in the hatchling chick by using horseradish peroxidase (HRP). HRP injections of the muscle showed that motor innervation arose, as expected, from the cervical motor column (C1–C6). However, additional innervation was also discovered; the spinal accessory nucleus (column of von Lenhossek), the nucleus supraspinalis, and the dorsal and ventral facial motor nuclei all contributed efferents to the hatching muscle. This observation constitutes the first description or dual innervation of a neck muscle by nuclei in both the brain and spinal cord. In addition, transganglionic transport of HRP revealed labelled primary afferent fibers from the hatching muscle ascending in the dorsal columns and terminating extensively within the vestibular complex, especially on the principal cells of the tangential nucleus. The tangential nucleus itself undergoes synaptic changes at the time of hatching. Possible functional relations between the tangential nucleus and the hatching muscle are discussed.