bluuebunny/crossref_metadata_2025 huggingface dataset:
The growth of muscle nerves in relation to the formation of primary myotubes in the developing chick forelimb
Authors: Noakes Peter G. , Everett Alan W. , Bennett Max R.
Published: January 2005

A study has been made of the development of muscle nerves to primary myotube clusters destined to become the flexor carpi ulnaris (fcu) and flexordigitorum profundus (fdp) muscles in the avian forelimb. Myotubes and nerves were identified by immunofluorescent techniques using antibodies to the heavy and light subunits of myosin and neurofilament, respectively. At stage24 the main ventral nerve trunk (the brachialis longus inferior nerve; bli n) had entered the limb before the appearance of myotubes in the limb. At stage 25/26 the bli n within the ventral compartment of the forearm had given rise to the interosseus nerve (in n) and the medial‐ulnar nerve (m‐u n) at the junction of the stylopodium and zeugopodium. The first few myotubes of the fdp and fcu muscles were observed at this level within the ventral premuscle cell mass; however, no nerves projected toward these myotubes from either the in n or the m‐u n at this time. At stage 26/27 the fcu and the fdp muscles each consisted of clusters of 20–40 myotubes; each cluster was clearly delineated within the ventral premuscle cell mass. By this time small groups of axons had left the in n and the m‐u n to grow into the fdp and fcu myotube clusters, respectively; these axons formed the muscle nerves. At stage 28/29 the number of primary myotubes in the clusters composing the fdp and fcu muscles had greatly increased, as did the size of the muscle nerves; each muscle was still clearly identifiable within the ventral muscle mass. By stage 32 the fdp and fcu muscles had clearly separated and the muscle nerves had divided into several well‐spaced branches within each muscle.

The present observations show that the main nerve trunks grow into the limb before the formation of myotubes expressing myosin isozymes. When myotubes do form they appear in small clusters at specific sites within the premuscle mass, before muscle nerves appear; a distinct muscle is destined to form from each of these clusters. Muscle nerves first branch from the main limb nerves when the myotube cluster contains more than about ten myotubes.
Laminar distribution of receptors in monkey (Macaca fascicularis) geniculostriate system
Authors: Shaw C. , Cynader M.
Published: January 2005

We have examined the laminar distributions of eight types of receptor in the primary visual cortex (area 17) and the lateral geniculate nucleus (LGN) of the macaque monkey. The receptor populations and subpopulations examined included those selective for γ‐aminobutyric acid (GABA) (using [3H]‐muscimol as ligand), L‐glutamate‐related receptors (using [3H]‐L‐glutamate and [3H]‐AMPA), muscarinic acetylcholine (using [3H]‐quinuclidinyl benzilate–NB and [3H]‐N‐methyl scopolomine–MS), cholecystokinin (CCK) (using [3H] pentagastrin), benzodiazepine (using [3H]‐flunitrazepam), and adenosine (using [3H]‐cyclohexyladenosine–CHA).

Each of the receptors examined exhibited characteristic and differing laminar patterns of binding in the striate cortex. Perhaps reflecting the high density of cell bodies and synapses in layer 4C, most receptors, except those labelled by [3H]‐L‐glutamate or [3H]‐AMPA, showed dense concentrations in this layer. Layers 4B and 5, which contain relatively few cell bodies and heavy myelin concentrations, were in general lightly labelled. Layer 6 showed relatively heavy labelling when [3H]‐AMPA (quisqualate) or [3H]pentagastrin (CCK) were used as ligands. The superficial layers of the cortex were zones of relative concentration of GABA, benzodiazepine, acetylcholine, glutamate‐related, and adenosine receptors. In general, the binding patterns resembled those previously described for cat visual cortex, but there were also some clear differences. The distributions of all of these receptors likely reflect the differential input substances to different laminae of the visual cortex.

Of the receptors examined, only those for GABA, benzodiazepine, and acetylcholine were found in substantial concentration in the LGN. Of these, GABA and benzodiazepine receptors showed especially dense binding in the magnocellular layers of the LGN compared to the parvicellular layers.
Distribution of γ‐aminobutyric acid‐immunoreactive neurons in the septal region of the rat brain
Authors: Onteniente Brigitte , Tago Hisao , Kimura Hiroshi , Maeda Toshihiro
Published: January 2005

The distribution of γ‐aminobutyric acid‐immunoreactive (GABA‐I) elements was examined in the septal region of the rat brain. The indirect peroxidase‐antiperoxidase technique was used with anti‐GABA antibodies in normal and colchicine‐pretreated rats, with or without use of detergent in the incubation medium.

Intraventricular injection of colchicine did not result in any change in the staining of neuronal perikarya. Intraseptal injections increased the intensity of labelling of GABA‐I cell bodies in the lateral septal nucleus and increased the number of labelled cells in the medial septal nucleus and diagonal band of Broca (dbB). Triton X‐100 added to the incubation media decreased the intensity of staining and number of GABA‐I somata in all septal nuclei with a concentration‐dependent effect. No change was observed concerning GABA‐I varicosities.

The septal area, including the lateral, medial, and triangular septal nuclei; the anterior rudiment of the hippocampus; the island of Calleja magna; the septofimbrial nucleus; the bed nucleus of the stria terminalis; and the dbB showed a strong reaction to anti‐GABA antibodies with regard to GABA‐containing surrounding structures. GABA‐I axonal varicosities were observed: in all the regions with an uneven distribution. The highest density was found in the dorsal and ventral parts of the lateral septal nucleus and in a band situated between the dbB and the nucleus accumbens. Labelled varicosities were frequently observed surrounding GABA‐I and nonimmunoreactive cell bodies.

GABA‐I somata ranged from 10 to 30μm in diameter. Small neurons were present in great number at the ventricular border and in the zona limitans. Medium‐size and large neurons were mostly observed in the medial part of the dorsal lateral nucleus and in the intermediate lateral nucleus. Large, strongly immunoreactive somata were revealed in the medial septum and dbB by intraseptal injections of colchicine.
Posthatching development of synapses in the neuropil of nucleus rotundus of the zebra finch: A quantitative electron microscopic study
Authors: Nixdorf Barbara , Bischof Hans‐Joachim
Published: January 2005

The development and maturation of synapses in the nucleus rotundus of the zebra finch were examined at 1, 5, 10, 20, and 100 days posthatching. Quantitative ultrastructural techniques were applied to investigate synaptic density, size of presynaptic terminals, and length of postsynaptic thickenings. During development there is a steady increase in the number of synapses and an enlargement of the presynaptic terminals. The length of the postsynaptic thickenings, however, decreases significantly during posthatching development. All three parameters reach adult values within 20 days of age. A close relationship was found between the enlargement of the presynaptic terminals and the increase in the number of contact zones up Lv the 20th day. The general feature of this developmental progress is in good agreement with biochemical and, to a certain extent, behavioral studies.
LHRH and catecholamine neuronal systems in the olfactory bulb of the mouse
Authors: Rosser Anne E. , Hökfelt Tomas , Goldstein Menek
Published: January 2005

The luteinizing‐hormone‐releasing hormone (LHRH) components of the mouse olfactory system were studied by using the indirect immunohistofluorescence technique. LHRH‐positive cell bodies were found in both the main olfactory bulb (MOB) and the accessory olfactory bulb (AOB); two distinct cell groups were found—one located adjacent to the AOB in the dorsal part of the MOB and a second in the superficial ventromedial aspect of the MOB. LHRH‐positive fibers were found predominantly in the posterior half of the main olfactory bulb innervating the olfactory nerve layer, the glomerular layer, the external plexiform layer, and the mitral cell layer, and small numbers innervated the AOB. The greatest density of LHRH‐immunoreactive fibers was seen adjacent to the AOB where one group of LHRH‐positive cells was noted.

Sections adjacent to those stained with LHRH antibody were analysed for tyrosine hydroxylase (TH) and dopamine β‐hydroxylase (DBH). The TH staining was intense for both cells and fibers in the glomerular layer of the MOB. In the AOB lower numbers of cell bodies and fibers were seen in the glomerular layer. The internal granular layer and internal plexiform layers were both stained, the internal granular layer showing more intensely fluorescent fibers with a higher density. Since no overlapping DBH‐positive fibers were found here, these TH‐positive nerve endings may be dopaminergic. DBH staining was confined to sparse networks of weakly fluorescent fibers with the highest numbers in the internal plexiform layer of the AOB and fewer fibers in the external plexiform, rostral, and granular layers of the MOB. Elution‐restaining experiments revealed that the LHRH‐positive and TH‐positive elements represent different cell populations.
Course of retinogeniculate projection fibers in the cat optic nerve
Authors: Naito Jumpei
Published: January 2005

The fiber courses of the cat optic nerve were studied by using wheat germ agglutinin conjugated to horseadish peroxidase (WGA‐HRP), which was iontophoretically applied to electrophysiologically defined positions in the lateral geniculate nucleus (LGN).

Grossly, there were two distinct bends along the legth of the optic nerve. The ventrally flexing anterior bend was located approximately 2 mm from the eyeball, while the dorsally flexing posterior bend was found at some 6 mm distant. The optic nerve fibers showed a tendency to scatter toward the chiasm. At the optic nerve head, the fibers from the different retinal areas maintained the retinal topography in a simpligfied form according to the trajectory of optic fibers surrounding the optic disc. Between the anterior and posterior bends, the fibers from the pericentral, middle‐temporal, and most upper areas of the dorsal retina migrated ventrally and were arranged in the middle of the lateral, middle, and medial parts of the optic nerve, respectively, while fibers from the middle‐temporal area of the ventral retina migrated dorsally and scattered into the lateral half. The fibers from the temporal and nasal horizontal meridian areas tended to hold their respective positions in the lateral and medial halves of the optic nerve. As a result, in this level they displayed a complex retinotopy in that the fibers from each part of the retina were mixed. Passing the posterior bend, as the optic nerve proceeded toward the chiasm, the characteristic pattern became less defined. Near the chiasm, the retinotopy became very scattered, showing a partial dorsoventral inversion of the retinal topography with substantial overlapping.

It was noted from the present findings that the fibers from ventral retina scattered more quickly than the fibers from the dorsal retina, which tended to hold their grouping until the anterior bend, but the central or pericentral retinal fibers proceeded without significant scatter as far as the posterior bend. The analysis of labelled ganglion cells suggested that even if fibers that arise from one certain “mode” of ganglion cells are selected, it is unlikely that they maintain their initial fiber topography along the entire length of the optic nerve.
Localization of glutamic‐acid‐decarboxylase‐immunoreactive axon terminals in the inferior olive of the rat, with special emphasis on anatomical relations between GABAergic synapses and dendrodendritic gap junctions
Authors: Sotelo C. , Gotow T. , Wassef M.
Published: January 2005

Immunocytochemical and electron microscopic methods were used to examine the GABAergic innervation of the inferior olivary nucleus in adult rats. This neuronal system was visualized with an antibody against glutamic acid decarboxylase (GAD, EC 4.1.1.15), the GABA‐synthesizing enzyme. A GAD‐positive reaction product was encountered only in short segments of preterminal axons and in axon terminals. Their relative number per unit area of neuropil was very similar in all olivary subnuclei. Despite this homogeneity in density, obvious intraregional differences existed. Some regions were strongly immunoreactive (the “c” subgroup, the ß nucleus, and the mediolateral outgrowth of the medial accessory olive), whereas others were weakly labeled (the dorsomedial cell column and the central zones of the medial accessory and principal olives). The strongly immunoreactive areas contained the largest and most intensively labeled axon terminals. Areas of weak labeling were filled with small, weakly immunoreactive nerve terminals. Thus, variations in size and in intensity of labeling create a specific pattern of GABA innervation, revealed by an almost continuous gradient between the above‐mentioned extremes.

The GAD‐positive axon terminals established conventional synapses with dendrites (94% of the samples) or with cell bodies (6%). The vast majority of these synapses were type II (84%) and only a small proportion formed type I synaptic contacts (16%), regardless of the nature of the postsynaptic element. Immunoreactive terminals were also involved in the complex synaptic arrangements‐‐‐the glomeruli, which characterize the olivary neuropil. Within these formations, olivary neurons were electrotonically coupled through dendrodendritic gap junctions. There was a constant association between GAD‐positive axon terminals and small dendritic appendages linked by gap junctions. This association was revealed not only by the systematic presence of immunolabeled terminals directly apposed to the dendritic appendages but, more importantly, by the frequent presence of type II synapses straddling both elements. These synapses were in close proximity to the low‐resistance pathways represented by the gap junctions. The strategic location of these GABA synapses is discussed in relation to recent findings indicating the possibility of a synaptic modulation of the electrical coupling: the release of GABA, by increasing nonjunctional membrane conductance, could shunt the coupling between olivary neurons. The functional decoupling of selected gap junctions would be responsible for the spatial organization of the olivary electrotonic coupling.
Morphology of physiologically identified bipolar cells in the retina of the tiger salamander, Ambystoma tigrinum
Authors: Hare William Alan , Lowe Janet S. , Owen Geoffrey
Published: January 2005

Intracellular recordings of the light responses of bipolar cells were made in the isolated perfused retina of the larval tiger salamander by microelectrodes filled with a 1% solution of the enzyme horseradish peroxidase (HRP). Two classes of bipolar cell were identified in terms of their responses to luminous spots and annuli centered upon their receptive fields: on‐center cells, which depolarized in response to a centered spot and hyperpolarized in response to a concentric annulus, and off‐center cells, which responded with the opposite polarities. Physiologically identified cells were labelled with HRP by iontophoretic injection and prepared for light microscopy. Examples of each of the three classes of bipolar cell described in Cajal's study of the amphibian retina were found amongst the labelled cells. The only morphological feature found to correlate with the physiological classification was the stratum at which the axon of the cell arborized in the inner plexiform layer. The axons of on‐center cells arborized in the more proximal sublamina b, while those of off‐center cells arborized in the more distal sublamina a. This is consistent with earlier findings in the retinae of the cat and the carp.
The distribution of dopamine immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko: An immunohistochemical study with antibodies against dopamine
Authors: Smeets Wilhelmus J. A. J. , Hoogland Piet V. , Voorn Pieter
Published: January 2005

The distribution of dopamine (DA) immunoreactivity in the forebrain and the midbrain of the lizard Gekko gecko was studied by using recently developed antibodies against DA. Dopamine‐containing cells were found around the glomeruli of the olfactory bulb, in several parts of the periventricular hypothalamic nucleus, in the periventricular organ, the ependymal wall of the infundibular recess, the lateral hypothalamic area and the pretectal posterodorsal nucleus of the diencephalon, and in the ventral tegmental area, the substantia nigra, and the presumed reptilian equivalent of the mammalian A8 cell group of the mesencephalon.

Dopaminergic fibers and terminals were observed throughout the whole brain, but particularly in the diencephalon and the telencephalon. The nucleus accumbens appears to have the most dense innervation, but also the striatum, amygdaloid complex, olfactory tubercle, septum, and dorsal ventricular ridge (especially its superficial zone) show numerous DA‐containing fibers and terminals. Except for the lateral cortex, cortical areas are not densely innervated by DA fibers.

In several respects DA distribution in the gekkonid brain differs from that in other reptiles studied. For instance, in the Gekko the dorsal ventricular ridge is densely innervated by DA fibers, whereas in turtles and crocodiles the same structure shows only weak catecholaminergic histofluorescence. When compared to the distribution of DA immunoreactivity in mammals, it appers that the DA system in the gekkonid telencephalon resembles the distribution of DA in the limbic forebrain and striatum of mammals. Whether these similarities in distribution of DA also imply similarities in function will be discussed.
Ultrastructure of mouse vallate taste buds: II. Cell types and cell lineage
Authors: Delay Rona J. , Roper Stephen D. , Kinnamon John C.
Published: January 2005

The lifespan of cells in the mouse taste bud was examined with high‐voltage electron microscopic (HVEM) autoradiography (ARG) after giving a single injection of 3H‐thymidine. Animals were killed at 1 hour, 6 hours, 12 hours, 24 hours, and then daily up through 10 days postinjection. Lingual tissues were prepared for HVEM ARG so that we could identify and characterize labeled cells. Four categories of taste cells were identified: basal, dark, intermediate, and light cells. Basal cells were polygonal cells located near the basolateral sides of the taste buds and were characterized primarily by the presence of filaments attached to the nuclear envelope. Dark and light cells had the typical features described by previous authors. Intermediate cells had features in between those of dark and light cells.

Over 90% of the cells labeled in the first 2 days following injection of 3H‐thymidine were basal cells. Labeled dark cells appeared 6 hours after injection, reached their peak incidence at the fourth day postinjection, and then gradually decreased. Labeled intermediate cells were identified after the appearance of dark cells (12 hours) and reached a peak incidence at the fifth day after injection of 3H‐thymidine. Lastly, labeled light cells were first observed on the fourth day postinjection and continued to increase until the tenth day, when they constituted 45% of the labeled cells. These data support the hypothesis that there is one cell line in the mouse vallate taste bud that undergoes morphological changes in its lifespan.
The projection of frontal cortical oculomotor areas to the superior colliculus in the domestic cat
Authors: Hartwich‐Young Rosi , Weber Joseph T.
Published: January 2005

The projection of frontal cortical oculomotor areas to separate laminae of the superior colliculus was examined in adult domestic cats. Following the placement of WGA‐HRP/HRP injections within the superficial, intermediate, and deep layers of the superior colliculus, several observations may be made regarding the frontal corticotectal projection in the cat. Large injections including all of the collicular layers result in the retrograde labeling of neurons in frontal cortical areas that have been suggested previously to be analogous to the frontal eye fields in monkeys. These areas are a portion of the ventral bank and lip of the cruciate sulcus, including a small portion of the medial wall of the hemisphere, and the medial and lateral banks and fundus of the presylvian sulcus. The same pattern of retrograde labeling in frontal cortical areas is seen when the injection sites are restricted to either the intermediate or deep collicular layers. That is, different frontal cortical areas of the cat project separately but not differentially upon different collicular laminae. The greates numbers of labeled neurons within frontal cortical oculomotor areas are observed following injections placed laterally within the caudal portion of the superior colliculus, regardless of whether the injection sites are located within the intermediate or deep collicular layers. Injections restricted to the superficial gray layer do not result in retrograde labeling in any of the frontal cortical oculomotor areas of the cat. These results are discussed in terms of the patterns of visuomotor integration specific to the cat, as well as in relation to previous evidence showing similarities between frontal cortical areas in cats and monkeys.
Effects of monocular deprivation on the cat's geniculate neurons projecting to both areas 17 and 18
Authors: Geisert Eldon E.
Published: January 2005

When a kitten is reared with one eyelid sutured closed, there are profound changes in the developing visual system. In the lateral geniculate nucleus, the neurons in the laminae innervated by the deprived eye are smaller than normal, and some of these neurons may lose connections with the visual cortex. In the present study a variety of double label retrograde transport methods were used to define the effects of monocular deprivation on cortical projections of geniculate neurons. One marker was injected into area 17 and the other was injected into area 18. Neurons projecting to area 17 are on average 16.4% smaller than those in the nondeprived laminae. The neurons that normally would project to both areas 17 and 18 by an axon that branches are the most severely affected by monocular deprivation. These cells are nearly 40% smaller than their counterparts in the nondeprived laminae, and many of the neurons appear to lose their projection to one of the cortical areas. These neurons may be at a distinct disadvantage, since they must compete with neurons from the nondeprived laminae for a considerable amount of cortical territory in two different cortical areas. This competition may be so severe that some of the neurons are no longer capable of maintaining connections with both cortical areas.
Neural inputs into the temporopolar cortex of the rhesus monkey
Authors: Morán M. A. , Mufson E. J. , Mesulam M.‐M.
Published: January 2005

Temporopolar cortex (TP) can be subdivided into agranular, dysgranular, and granular components. The telencephalic input into the temporopolar cortex arises from the orbitofrontal and medial frontal regions, modality‐specific visual and auditory association areas, paralimbic regions, the piriform olfactory cortex, the hippocampus, the amygdala, the claustrum, and the basal forebrain.

Afferents from limbic and paralimbic regions are directed mostly to the agranular and dysgranular sectors of the temporal pole, whereas afferents from isocortical association areas are distributed predominantly within the granular sector.

The temporopolar cortex provides a site for the potential convergence of sensory and limbic inputs. Auditory inputs predominate in the dorsolateral part of the temporopolar cortex whereas visual inputs become prominent only in the ventral portions of this region. Olfactory inputs are directed mostly to the medial parts of the temporal pole. These medial parts also receive more extensive projections from the amygdaloid nuclei.
Spatial distribution of axon collaterals of single inferior olive neurons
Authors: Rosina A. , Provini L.
Published: January 2005

The aim of this study was to define the overall distribution pattern of the axon collaterals of single inferior olive (IO) neurons in relation to the multiple somatotopic maps defined by the climbing fiber (CF) input through the cerebellar cortex.

In a previous study (Rosina and Provini: Brain Res. 289:45–63, '83), it was shown that the IO neurons supply interlobar collaterals to pairs of somatotopically related areas in the intermediate part of the anterior lobe (PIAL), in the paramedian lobule (PML), in crus II, and in the simple lobule, within strips C1 to D2. The residual branches then could either distribute within single folia or to adjacent folia within each somatotopically defined cerebellar area or both. We studied whether or not the IO axons branch over neighboring folia of the face‐forelimb (FL) areas of PIAL and PML and how this interfolial branching relates to the interlobar collateralization by using the multiple fluorescent retrograde tracing technique.

The main results of the study were as follows: (1) the axons from neurons in IO subdivisions that are related to strips C1–C3 give off two interfolial branches in the FL area of PIAL and practically no interfolial collaterals are given in the FL area of PML; and (2) the neurons that give off interfolial collaterals also give interlobar branches.

From these data we have inferred the general branching pattern of the IO neurons that convey FL information to PIAL and PML. Each neuron gives off two interlobar collaterals: the branch directed to PIAL splits again into two interfolial collaterals, while each of these three collaterals should give off about three branches within each target folium to account for the ten collaterals estimated to be present in the cat.

The distribution pattern of IO axon collaterals proposed here suggests that the same CF‐relayed information may interact, at the Purkinje cell level, with different sets of mossy fiber inputs. The effect of this interaction would be to modulate the motor commands forwarded to specific muscle groups in relation to the different conditions under which a given movement is executed.
Distribution and partial characterization of FMRFamide‐like peptides in the stomatogastric nervous systems of the rock crab, Cancer borealis, and the spiny lobster, Panulirus interruptus
Authors: Marder Eve , Calabrese Ronald L. , Nusbaum Michael P. , Trimmer Barry
Published: January 2005

The distribution of FMRFamide‐like peptides was studied in the complete Stomatogastric nervous system [the paired commissural ganglia, single oesophageal ganglion, and the single Stomatogastric ganglion (STG)] of two decapod crustacean species, the spiny lobster Panulirus interruptus and the rock crab Cancer borealis, by using immunocytochemical techniques. Antiserum 231 from the O'Donohue laboratory and antiserum 671C (described here) gave essentially the same staining patterns.

In the commissural ganglia of both species there were ten to 20 stained neurons and dense neuropilar staining. The oesophageal ganglion of the crab had four stained neurons. Lucifer Yellow backfills followed by immunostaining showed that the two larger stained neurons of the oesophageal ganglion sent processes into the inferior ventricular nerve. The two smaller neurons sent processes into the inferior oesophageal nerves. The oesophageal ganglion of the lobster had two stained neurons that sent processes into the inferior ventricular nerve as well. None of the somata of the STG stained in either species, but in both species stained fibers were seen in the Stomatogastric nerve that entered the STGs and ramified profusely throughout the neuropil. In some preparations of the crab, a stained fiber was visible in the dorsal ventricular nerve.

The amounts of the FMRFamide‐like peptides found in all regions of the nervous system of P. interruptus and C. borealis were determined by radioimmune assay (RIA). Column chromatography and high‐performance liquid chromatography suggest that, in both species, much if not all of the RIA‐assayable material is accountable for by peptides that are larger and more hydrophobia than FMRFamide.
Amygdalofugal and amygdalopetal connections with modality‐specific visual cortical areas in macaques (macaca fuscata, M. mulatta, and M. fascicularis)
Authors: Iwai Eiichi , Yukie Masao
Published: January 2005

The origins and terminations of the amygdaloid connections with the modality‐specific visual cortical areas TEa (anterior TE area), TEp (posterior TE area), TEO, V4, V2, MST (medial superior temporal visual area), MT (middle temporal visual area), and V1 were studied in macaques. These were compared with the amygdaloid connections of a vision‐related polysensory area TG by making cortical injections of horseradish peroxidase (HRP) and incubating the sections with tetramethylbenzidine (TMB) as the chromogen. Both areas TEa and TEp receive a major projection from the lateral basal nucleus and a minor one from the accessory basal nucleus of the amygdaloid complex, whereas these areas send a major projection to the lateral nucleus and a minor one to the lateral basal nucleus. Areas TEO, V4, V2, MST, MT, and V1 receive projections only from the lateral basal nucleus; none of them project to any amygdaloid nucleus. Thus, the amygdalofugal projections are more widespread and more complex than the amygdalopetal projections. These findings indicate that the connections between the amygdaloid nuclei and the visual areas are generally nonreciprocal and underlie the importance of a feedback mechanism from the amygdala to the visual cortical areas in visual information processing. There appears to be a caudorostral (occipitotemporal) gradient in the distribution and density of the amygdaloid projections, which become progressively more widespread and heavier among the progressively more rostral visual areas (from area V1 to area TEa).

The amygdaloid connections with area TG are distinctly different from the connections with the visual areas. Area TG is reciprocally connected mainly with the periamygdaloid cortex, and with the lateral, accessory basal, and medial basal nuclei of the amygdala as well.
Localized changes in olfactory bulb morphology associated with early olfactory learning
Authors: Woo Cynthia C. , Coopersmith Robert , Leon Michael
Published: January 2005

Young rats exposed to an odor while receiving reinforcing stimulation come to approach that odor upon subsequent presentation. In addition, such pups have increased 14C‐2‐deoxyglucose (2DG) uptake within focal areas of the glomerular layer in response to that odor, compared to control animals experiencing the odor for the first time. In this study, the morphology of the glomerular areas underlying these 2DG foci was examined to determine whether early olfactory learning imposed local structural changes that could produce the enhanced 2DG uptake. Alternate sections either were processed with a silver and a Nissl stain to label both cell bodies and their processes or were histochemically treated for the mitochondrial enzymes cytochrome oxidase (CO) or succinic dehydrogenase (SDH) to define the glomerular core of the bulb; 2DG autoradiographs were aligned with adjacent stained sections, and regions underlying the high 2DG uptake foci were examined. In odor‐familiar animals, large glomerular clusters that protruded into the external plexiform layer or the olfactory nerve layer were associated with the focal areas of increased 2DG uptake. Morphometric analysis of these regions revealed that the glomerular layer underlying the foci of high 2DG uptake was 30% wider in odor‐familiar animals than comparable areas in odor‐unfamiliar animals; the cross‐sectional areas of individual glomeruli were 21% larger in odor‐familiar animals. The foci of enhanced 2DG uptake therefore appear to be associated with groups of enlarged glomeruli. These data demonstrate that early olfactory learning influences the morphology of the olfactory bulb.
Effects of a lengthy period of undernutrition from birth and subsequent nutritional rehabilitation on the synapse: Granule cell neuron ratio in the rat dentate gyrus
Authors: Ahmed M. G. E. , Bedi K. S. , Warren M. A. , Kamel M. M.
Published: January 2005

Recent evidence showing alterations in spatial memory due to a period of undernutrition during early life has implicated the hippocampus as one of the brain centres that may be particularly adversely affected. However, there arc very few quantitative morphological studies that have examined the neuronal and synaptic populations of the hippocampi from undernourished animals. We decided to carry out such experiments, paying particular attention to the granule cell of the dentate gyrus.

Male rats were undernourished from the 18th day of gestation until 21, 75, or 150 days or age. Some of these previously undernourished rats were nutritionally rehabilitated between 150 and 250 days of ago. Groups of wellfed control and experimental rats were killed by intracardiac perfusion with 2.5% sodium‐cacodylate‐buffered glutaraldehyde. The right hippocampus from each rat was dissected out and processed for electron microscopy. Stereological procedures at the light, and electron microscopical levels were used to estimate the numerical densities of granular cell neurons and molecular layer synapses in the dorsal lip of the dentate gyrus. These estimates were used to calculate synapse: neuron ratios.

There were 5,056 ± 347 (mean ± SE) and 5,002 ± 190 synapses per neuron in 21‐day‐old control and undernourished rats, respectively. By 75 days these values had increased to 9,215 ± 588 and 6,683 ± 237. The difference was statistically significant. By 150 days of age the value for control animals had fallen once again to 6,518 ± 209 whereas undernourished rats had increased slightly to 7,689 ± 288 (P <.01); 250‐day‐old rats, previously undernourished from birth to 150 days of age, showed a substantial increase in the synapse: neuron ratio during the period of nutritional rehabilitation. Thus these nutritionally rehabilitated rats had 9,407 ± 365 synapses per neuron whereas age‐matched controls had only 6,323 ± 239 (P <.01).

These ressults indicate that the rat dentate gyrus is vulnerable to undernutrition even during the postweaning period and that a lengthy period of undernutrition can alter the developmental growth curve for synapse: neuron ratios.
Response of septal cholinergic neurons to axotomy
Authors: Armstrong David M. , Terry Robert D. , Deteresa Richard M. , Bruce Gordon , Hersh Louis B. , Gage Fred H.
Published: January 2005

In the present study we employed quantitative morphometric techniques to assay the response of septal cholinergic neurons following unilateral transection of the fimbria/fornix and supracallosal stria. Analysis of 50‐μm‐thick tissue sections with a Quantimet 920 image analysis system demonstrated a reduction in ChAT immunoreactivity as early as 1 day following denervation. This decrease was associated with a drop in the number of labeled cells ipsilateral to the lesion and a decrease in the area of cholinergic perikarya on the lesioned and nonlesioned side of the septum. The response at 1 day, however, was transient, and at 4 days the number of labeled neurons was not significantly different from controls. By 8 days we observed a dramatic reduction in the number and size of ChAT‐positive cells ipsilateral to the lesion and a reduction in the size of cholinergic perikarya on the contralateral (i.e., nonlesioned) side. These values persisted throughout the remainder of the study.

To assess more completely the morphologic response of neurons to axotomy than can be determined in 50‐μm‐thick tissue sections, we embedded the adjacent immunolabeled tissue section in Epon and then serially sectioned it to a thickness of 0.75–1.0 μm. By using this method, we wore able to measure the area, length, and width of the cell, the area of the nucleus and nucleolus, and the position of the nucleus (i.e., eccentricity). Measurements were performed on ChAT‐labeled and nonlabeled cells. The results of our studies demonstrate that cholinergic and noncholinergic cells responded to axotomy in a characteristic yet different fashion from each other and that this response could be quantitatively assayed. In general, labeled and non‐labeled cells on the lesioned side of the septum shrink in response to denervation. This shrunken state was reflected in measurements of cellular area, length, width, and nuclear area. Moreover, other measurements of cellular morphology (i.e., area of the nucleolus, position of the nucleus) indicate that none of the neuronal populations examined in the present study displayed morphologic evidence of regeneration.

Our results indicate a dramatic loss of cholinergic perikarya ipsilateral to the lesion. Moreover, although a few neurons do persist they do so in a shrunken state. These data provide an essential baseline for the second study in this series, which will evaluate the effect of nerve growth factor on the survival of denervated septal neurons.
Selective projections from the cat red nucleus to digit motor neurons
Authors: McCurdy M. L. , Hansma D. I. , Houk J. C. , Gibson A. R.
Published: January 2005

Classical studies of the cat rubrospinal tract describe dense terminations in spinal laminae V–VII and an absence of any significant projection to lamina IX. In contrast, our recent studies, utilizing the anterograde transport of wheat germ agglutinin conjugated with horseradish peroxidase, have demonstrated a consistent and circumscribed area of label in lamina IX at caudal cervical segments.

The present study was undertaken to determine the distribution of rubrospinal terminals among motor neurons in lamina IX as well as to identify the likely target muscles of those motor neurons located near rubrospinal terminals. We injected wheat germ agglutinin‐horseradish peroxidase into the red nucleus and unconjugated horseradish peroxidase into selected forearm muscles of the same side of the body. The locations of rubrospinal terminals showing anterograde label on one side of the spinal cord could then be compared with the locations motor neurons showing retrograde label on the opposite side of the cord.

The results demonstrated a clear focus of rubrospinal terminals in the lateral and dorsal portions of the ventral horn beginning at C8 and extending through rostral T1. No other segments of the spinal cord showed a focus of rubrospinal terminations in lamina IX. Retrogradely labeled motor neurons from the muscle injections showed that the rubrospinal terminals overlap extensively with motor neuronal pools supplying distal forearm muscles. Several lines of evidence indicate that the terminals are from rubrospinal fibers and are not due to transneuronal transport.
Characterization of HRP‐labeled globular bushy cells in the cat anteroventral cochlear nucleus
Authors: Smith Philip H. , Rhode William S.
Published: January 2005

We report on the anatomical and physiological features of globular bushy cells in the posterior division of the anteroventral cochlear nucleus based on the characteristics of 20 cells from this population. Each of these cells was recorded from and characterized intracellularly and/or extracellularly, injected with horseradish peroxidase, and studied at the light and/or electron microscopic level. Intracellular records from the vicinity of the globular bushy cell body displayed large, fast synaptic potentials, and in some instances a larger presumed action potential both in silence and during short tone stimulation. Intraaxonal recordings displayed large action potentials in addition to small, fast potentials, which evidence indicates may be the decrementally conducted subthreshold synaptic potentials. Both recording situations indicated that these auditory nerve inputs need not be suprathreshold. Bushy cells with high characteristic frequencies (CFs > 3 kHz) typically showed primary like‐ with‐notch responses to short tones at CF or on‐type L responses if the sustained level of discharge after the notch was not as robust. Low‐CF bushy cells phase‐locked after a well‐timed onset spike. Light microscopic anatomy revealed a typically oval cell body giving rise to one or two primary dendrites that branched profusely and an axon that gave off no collaterals within the cochlear nucleus before entering the trapezoid body. Electron microscopic analysis showed a high concentration of large, round, vesicle‐containing terminals on the cell body and primary dendrite while the population of terminals on the initial segment and sparsely covered distal dendrites was made up mostly of flat and pleomorphic vesicle‐containing terminals.
Postnatal development of interstitial (subplate) cells in the white matter of the temporal cortex of kittens: A correlated Golgi and electron microscopic study
Authors: Valverde F. , Facal‐Valverde M. V.
Published: January 2005

The early postnatal development of interstitial cells (IC) in the white matter of the temporal cortex in kittens was studied. Counts in Nissl‐stained preparations show that the number of 1C diminishes by about 60% during the second postnatal week. In Golgi preparations, IC are bipolar or bitufted with long, beaded dendrites coursing in the white matter toward the ventricular surface. Ascending, shorter dendrites are thinner, often branch in a short bush, and possess long spines resembling filopodia. The majority of their axons descend in the white matter, emitting numerous recurrent collaterals that become ascending fibers reaching various cortical layers. Most 1C resemble inverted pyramidal cells. They appear well developed at the time of birth and continue to develop elaborate axonal complexes in the white matter of older animals. Electron microscopic observations of degenerating 1C were detected in all cases studied and their presence was related to the existence of cell death responsible for elimination of a fraction of 1C. They were recognized by their dark aspect and by dilations of the endoplasmic reticulum. Synapses contacting degenerating profiles were also observed. It is concluded that 1C belong to the population of early generated subplate cells which may have a transient function involved in certain morphogenetic events during the development of the cortical plate. Some persist in the adult where they can be recognized as IC of the white matter.
Organization and synaptic relationships of the projection from the primary sensory to the primary motor cortex in the cat
Authors: Porter Linda L. , Sakamoto Kuniyo
Published: January 2005

It is known from previous studies that fibers originating from cells in area 2 of the cat primary somatosensory cortex project topographically to area 4 of the motor cortex and that they terminate preferentially in the caudal region of the cruciate sulcus. We examined this pathway to determine more precisely the distribution pattern of fibers and the laminar arrangement of axon terminals in the motor cortex. The recently developed technique of PHA‐L staining enabled us to label anterogradely the axons that form this projection. Iontophoretic injections of PHA‐L were made into the rostral bank of the ansate sulcus (area 2). After 7 days the cats were perfused and the tissue was processed immunohistochemically to stain the PHA‐L filled fibers. Light microscopic examination revealed that a small cluster of cells in the sensory cortex gave rise to multiple foci of labeled axons in area 4. The labeled fibers formed columnlike arrays, which were located for the most part in the posterior bank of the cruciate sulcus and were separated by irregular intervals of cortex devoid of labeled fibers. Clusters of labeled fibers were also found in the anterior region of the cruciate sulcus in some of the animals. The dimensions of the labeled areas and the small number of cells that gave rise to each group of fibers suggested that axonal branches of cells within the injection site formed the multiple foci. Variations in the immunohistochemical staining enabled us to study the laminar distribution of sensory cortex axon terminals with the electron microscope. Whereas some PHA‐L labeled terminals were found in the deep cortical layers, the majority (82%) were spread throughout layers I–III. Differences in the laminar distribution of sensory cortex afferents that formed axodendritic or axospinous synapses were noted. Synapses formed with dendritic shafts were relatively sparse (28%) and were confined to the superficial layers. Some of the more numerous axospinous synapses, which accounted for 72% of identified synapses, were found in layers V and VI, although most were in layers I–III. The distribution pattern of terminals showed little variation between columns in different areas of the motor cortex, including that in the anterior cruciate region. The pattern of termination of the sensory to motor cortex projection is discussed in relation to the physiological characteristics of this pathway.
Immunocytochemical and morphological evidence for a retinopetal projection in anuran amphibians
Authors: Uchiyama Hiroyuki , Reh Thomas A. , Stell William K.
Published: January 2005

The centrifugal projection to the retina in anuran amphibians (Rana catesbeiana and Xenopus laevis) has been investigated by immunocytochemistry, HRP transport, and optic nerve lesionings. FMRFamide‐ and N‐terminal substance P–immunoreactive (Fa‐ir and SP(3–7)‐ir) fibers were abundant in the normal retina and optic nerve but almost absent distal to an optic nerve section or crush after 7–14 days survival. Fa‐ir and SP(3–7)‐ir fibers were traced to the optic nerve from the lamina terminalis (or the septopreoptic junctional area), where there are many Fa‐ir and SP(3–7)‐ir perikarya. After application of HRP to the optic nerve and survival for 9–10 days, retrogradely labeled neurons were observed in the lamina terminalis. Conversely, following HRP injection into the septal and preoptic area, labeled fibers were observed in the optic nerve. These results suggest that Fa‐ir and SP(3–7)‐ir efferent fibers project from the lamina terminalis to the retina. But in anurans, unlike teleosts, these fibers are not gonadotropin‐releasing‐hormone (GnRH)‐ir. The morphological relations of this retinopetal pathway with the GnRH‐ir nervus terminalis are discussed.