bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of acetylcholinesterase activity in the lateral geniculate nucleus
Authors: Hutchins James B. , Casagrande Vivien A. 
Published: January 2005

AbstractThe pattern of acetylcholinesterase activity in the tree shrew (Tupaia belangeri) lateral geniculate nucleus (LGN) undergoes a number of striking changes during postnatal development. The adult tree shrew LGN is made up of six cellular layers divided by relatively cell‐free interlaminar zones. At birth, however, the nucleus appears unlaminated when processed with conventional Nissl‐staining techniques. The cellular lamination appears during the first postnatal week. The eyes open much later, typically at the end of the third week after birth.In the adult tree shrew, acetylcholinesterase (AChE) activity is found throughout the nucleus (both within and between the six cellular layers). In most sections examined, reaction product is slightly more intense in the lateral cell layers (4, 5, and 6).This is in sharp contrast to the pattern at birth (postnatal day zero, or P0). The detectable AChE activity at this age is apparently found in inchoate layers 1‐2 and 4‐5. Within these pairs, areas innervated by the ipsilateral eye (i.e., incipient layers 1 and 5) appear to contain more reaction product. From P0 to P4, the density of AChE activity increases in layers 1‐2 and 4‐5 and becomes detectable in the barely evident layers 3 and (usually) 6 at this age. By the middle of the second postnatal week, after laminae are clearly apparent with a Nissl stain, AChE activity has increased and is mainly associated with each cellular layer in the nucleus. During the third week after birth this pattern undergoes a radical shift. The most intense AChE activity is now in the interlaminar zones. Finally, as the adult pattern emerges, AChE activity increases in the cellular layers and all areas of the nucleus exhibit relatively high levels of AChE activity.Superimposed on this changing laminar pattern of AChE activity are changes related to the retinotopic map within the nucleus. Portions of the LGN representing central vision develop their characteristic pattern of activity several days ahead of the regions representing more peripheral visual field locations.AChE activity is also found transiently in the optic tract near the LGN during the first 3 postnatal weeks. Two (possibly three) groups of AChE‐carrying fibers can be traced from the optic chiasm to their apparent sites of termination (or origin) in the parabigeminal nucleus, ventral lateral geniculate nucleus, and dorsal LGN. The activity present in the optic tract disappears shortly after eye opening.These results suggest that AChE and/or its associated neurotransmitter, acetylcholine, may play a role in the sequential development of connections and lamination in the LGN. The observed shifting pattern of AChE activity is consistent with a morphogenetic role for the enzyme, as suggested by others. However, it may also simply reflect the establishment and neurochemical maturation of cholinergic synapses during development of the LGN.
Fine structure of identified neurons in the primate hippocampus: A combined Golgi/EM study in the baboon
Authors: Frotscher Michael , Kraft Jürgen , Zorn Uwe 
Published: January 2005

AbstractThe hippocampi of two 1‐year‐old female baboons (Papio anubis) were used for a combined Golgi/electron microscope (EM) study of characteristic cell types in the hippocampus proper and fascia dentata. Results were compared with previous Golgi/EM studies of hippocampal neurons in small laboratory animals.Cell bodies of pyramidal neurons in CA1 were more loosely distributed than known from studies on the rat or guinea pig. Numerous basal and horizontal dendrites originating from the perikaryon filled in the space between neighboring cell bodies. Apical stem dendrites were varying in length, depending on the position of the parent cell body in outer or inner portions of the pyramidal layer. Dendrites were densely covered with spines which in the EM showed very complex synaptic contacts.In contrast to our observations in rats and guinea pigs, CA3 pyramidal cells in the monkey hippocampus exhibited numerous large spines orexcrescences not only on apical dendrites but also on basal dendrites running through stratum oriens. These excrescences appeared to be more complex than in small rodents. They often branched, protruding deeply into presynaptic mossy fiber boutons, and formed multiple asymmetric synaptic contacts.Granule cells of the monkey fascia dentata, in contrast to those of the rodent, occasionally had basal dendrites extending into the hilar region. In the EM, granule cells either with or without basal dendrites exhibited fine structural characteristics that were very similar to those described in Golgi/EM studies of granule cells in the rat fascia dentata.Of the various types ofnonpyramidal neurons the horizontal cells in stratum oriens with dendrites parallel to the alveus were analyzed. As seen in rats, these cells exhibited large amounts of rough endoplasmic reticulum, indentations of the nuclear membrane, and nuclear inclusions. Numerous terminals formed synaptic contacts on dendritic shafts. In contrast to rodents, numerous spines arose from dendrites and cell bodies of these neurons. In the EM, often single spines were found to establish synaptic contacts with several presynaptic boutons.In summary, our correlated light and EM study of four characteristic cell types, which are present in both nonprimates and primates, demonstrates a much more complex dendritic pattern and synaptic organization of these neurons in primates than in commonly studied small laboratory animals.
Synaptic analysis of amacrine cells with neuropeptide Y‐like immunoreactivity in turtle retina
Authors: Isayama Tomoki , Polak Julia , Eldred William D. 
Published: January 2005

AbstractNeuropeptide Y‐like immunoreactivity has been localized previously within three classes of amacrine cells in the turtle retina. We have used the avidin‐biotin with horseradish peroxidase technique to label these neurons for examination at the ultrastructural level to answer the following questions. Where are the synaptic contacts of these neurons made? What types of neurons are involved pre‐ and postsynaptically? What is the intracellular distribution of the immunoreactivity?Processes with neuropeptide Y‐like immunoreactivity were located primarily within three regions of the inner plexiform layer: stratum 1, stratum 3, and at the border between strata 4 and 5. In all three regions the processes with neuropeptide Y‐like immunoreactivity received synaptic contacts from both unlabeled amacrine and bipolar cells, but the majority of the synaptic input in all three regions was from unlabeled amacrine cells. Processes with neuropeptide Y‐like immunoreactivity were presynaptic to unlabeled amacrine cells in all three regions, but also formed contacts onto unlabeled bipolar cells in the region between strata 4 and 5.The immunoreactivity within these cells gave rise to a diffuse reaction product that was distributed throughout the cytoplasm and within large vesicles. This localization of neuropeptide Y‐like immunoreactivity within large vesicles suggests that this peptide may play a neuromodulatory role. Such a role would be consistent with previous studies of neuropeptides in the turtle retina.
Feline islands of calleja complex: I. Cytoarchitectural organization and comparative anatomy
Authors: Talbot Konrad , Woolf Nancy J. , Butcher Larry L. 
Published: January 2005

AbstractCytoarchitectural analyses demonstrated that the islands of Calleja complex (ICC) is highly developed and discretely organized in the cat. The feline complex is clearly divided into morphological units, each containing a granular Callejal island and a population of satellite neurons. These ICC units change progressively in cytoarchitecture from the lateral to the medial edge of the olfactory tubercle. In particular, the islands flatten, sink into the tubercular molecular layer, and increase in cell density, while their satellite neurons increase in number and decrease in size. The lateromedial transformation was judged to take place in five stages, resulting in the successive appearance of lateral, lateral transitional, central, medial transitional, and medial ICC units. The first two unit types display prominently two additional components of the feline ICC‐‐‐namely, clusters of dwarf cells and small pyramidal‐like neurons constituting the densocellular layer cupping the base of lateral Callejal islands.All of the various types of ICC units contact the tubercular molecular layer via their dwarf and/or granule cell components, raising the possibility of direct olfactory input to the entire Callejal complex (apart from the isla magna). Output from the complex is presumed to arise from the satellite neurons, which are distinguished from adjoining cell populations by their close association with Callejal islands, typical chromophilic character, and relatively large size (15‐42 μm in soma length). In the tubercular ICC, these neurons are most numerous immediately above Callejal islands in a fiberrich zone continuous with the supratubercular zone and hence with the ventral pallidum. In the accumbal ICC, satellite neurons are most conspicuous in granule‐cell‐poor spaces within the isla magna, where many nongranular neurons are uncharacteristically small and chromophobic. The isla magna itself is unusual not only for its large size but for lateral extensions encircling a group of accumbal neurons far caudally. Such extensions are one of several indications that the isla magna is intimately associated with the nucleus accumbens.A comparative anatomical survey of the ICC in rats, cats, and macaque monkeys demonstrated a number of species differences. Of particular interest is the finding that the complex is unambiguously divided into discrete island‐satellite cell units only in cats and macaques. In these species, the complex is also distinguished by a predominance of superficial islands and an especially prominent isla magna. ICC units, however, were most conspicuous in cats.
Estrogen/progesterone treatment in adulthood affects the size of several components of the medial preoptic area in the male rat
Authors: Bloch G. J. , Gorski R. A. 
Published: January 2005

AbstractThe results of preliminary studies suggested that steroid and/or propylthiouracil (PTU) treatment of adult gonadectomized (Gxd) male rats significantly reduced the volume of the sexually dimorphic nucleus of the preoptic area (SDN‐POA). Therefore, we designed a study to examine this effect in detail. Groups of adult rats were sham Gxd (intact) or Gxd, then treated with multiple injections of oil (males and females), or estrogen and progesterone (males). Gonadectomized estrogen/progesterone‐treated males had a significantly smaller SDN‐POA volume, smaller volume of the medial division of the medial preoptic nucleus (MPNm), smaller volume of the anteroventral MPNm (MPNav), and larger volume of the anteroventral periventricular nucleus (AVPv). The volume of the central division of the medial preoptic nucleus (MPNc) or of the suprachiasmatic nucleus was not affected. There were no differences between Gxd estrogen/progesterone‐treated males vs the group that received PTU as well, indicating that the PTU treatment was unnecessary. The reduced volume of the SDN‐POA was due to a reduced volume of the MPNav and of the portion of the SDN‐POA located within the MPNm‐exclusive of the MPNav and MPNc. In conclusion, estrogen/progesterone treatment in adulthood caused significant changes in the volume of several medial preoptic structures in two separate groups of Gxd males. Because the steroids produced no significant effects in intact males, testicular hormones appear to “protect” these structures from the effects of the estrogen/progesterone treatment.
Hormonal modification of the number of total and late‐arising neurons in the central part of the medial preoptic nucleus of the rat
Authors: Dodson Robin E. , Shryne James E. , Gorski Roger A. 
Published: January 2005

AbstractThe sexually dimorphic nucleus of the preoptic area (SDN‐POA) is larger in volume in males, is responsive to steroids developmentally, and contains a subpopulation of late‐arising neurons that can be specificially labeled with 3H‐thymidine on embryonic day 18 (E18). The cytoarchitecture of this region has been described, and one component, the central part of the medial preoptic nucleus (MPNc), shows considerable overlap with the SDN‐POA. One goal of the present study was to relate the two by determining if testosterone propionate (TP) exposure perinatally increases MPNc volume and neuronal number, and by characterizing the distribution of the late arising neurons of the SDN‐POA with respect to the MPNc. A second goal was to determine if these late‐arising neurons are a representative, hormone‐sensitive population. Finally, TP exposure was delayed past the time of the endogeneous testosterone surge in males and after the neurons have become postmitotic, to determine if female brain structure could still be sex‐reversed under these conditions. Pregnant rats were injected on E18 with 3H‐thymidine. Daily injections of 2.0 mg TP were given to the mothers starting on either E16 or E20 and continued through birth. The pups were injected daily with 100 μg TP from birth through postnatal day 10. Control rats, from mothers given oil from E16 until birth, were injected with oil from birth through postnatal day 10. Rats were sacrificed at 30 days of age and their brains processed for autoradiography. Neurons and labeled cells were counted in three areas: (1) the MPNc, (2) the region surrounding the MPNc, and (3) a region anterior to the MPNc within the SDN‐POA. Labeled cells composed approximately 16% of the neurons in the MPNc and only 3 to 4% in the control regions. Within the MPNc there were more neurons and labeled cells in males than in females. Testosterone treatment, regardless of the starting day, increased MPNc volume and its number of neurons and labeled cells to those of males. These data demonstrate that there is a sex difference in the number of late‐arising neurons at 30 days of age, that they are sensitive to steroids during development, and that they are localized to the MPNc. In addition, TP exposure is effective beyond the time of the endogeneous surge in males. Steroid injections in one group of animals were not started until neurons in this region had become postmitotic but still resulted in a sex‐reversal, suggesting that testosterone does not modify neurogenesis.
Efferent connections of the striatum and the nucleus accumbens in the lizard Gekko gecko
Authors: Russchen Fokje T. , Jonker Allert J. 
Published: January 2005

AbstractThe efferent connections of the striatum and the nucleus accumbens of the lizard Gekko gecko were studied with the anterograde tracer Phaseolus vulgaris‐ leucoagglutinin (PHA‐L). These structures were found to have segregated output systems. The striatum shows a major projection to the globus pallidus. Striatal fibers which are more caudally directed run through the lateral forebrain bundle and can be traced as far caudally as the pars reticularis of the substantia nigra where they exhibit many varicosities. Along its course, the lateral forebrain bundle issues fibers with varicosities to the anterior and posterior entopeduncular nuclei. The major recipient structure of the nucleus accumbens is the ventral pallidum. The nucleus accumbens, in addition, projects to the portion of the lateral hypothalamus in the path of the medial forebrain bundle and to the ventral tegmental area, which is its most caudal target.Subsequently, the same technique was used in an attempt to study the efferents of the globus pallidus and the ventral pallidum, the major recipient structures of the striatum and the nucleus accumbens. The globus pallidus was found to project to the rostral part of the suprapeduncular nucleus in the ventral thalamus and, in addition, may distribute fibers to the same structures as does the striatum. The ventral pallidum distributes fibers to the ventromedial thalamic nucleus. It probably also projects diffusely to the hypothalamus, the habenula, and the mesencephalic tegmentum.
Anatomical and functional organization of the prepacemaker nucleus in gymnotiform electric fish: The accommodation of two behaviors in one nucleus
Authors: Kawasaki M. , Maler L. , Rose G. J. , Heiligenberg W. 
Published: January 2005

AbstractThe diencephalic prepacemaker nucleus (PPn) of gymnotiform electric fish projects to the medullary pacemaker nucleus and modulates its regular firing frequency. Each firing of the pacemaker, in turn, drives an electric organ discharge (EOD) Two types of PPn neurons were retrogradely labeled from the pacemaker with HRP in Eigenmannia and Apteronotus. In both species, smaller ovoidal cells were found in the dorsomedial part of the PPn (PPn‐G), and larger multipolar cells were found in the ventrolateral part of the PPn (PPn‐C). This morphological distinction between the two subnuclei in the PPn was paralleled by a functional dichotomy. Microiontophoresis of L‐glutamate in the PPn‐G of both species elicited slow and gradual accelerations of EOD frequency characterized by a time constant on the order of seconds. The elicited frequency modulations were similar to those observed during the jamming avoidance response and during courtship. Glutamate stimulation of the PPn‐C, in contrast, produced fast and abrupt frequency modulations characterized by a time constant on the order of milliseconds. These abrupt modulations resembled “chirps” observed during courtship and aggression. Similar behavior was produced by intracellular current injection into a PPn‐C neuron of Apteronotus, and intracellular labeling of this neuron with Lucifer Yellow revealed a multipolar PPn‐C neuron similar to those retrogradely labeled with HRP.
Immunocytochemical localization of gamma‐aminobutyric acid (GABA) in the cat superior colliculus
Authors: Ranney Mize R. 
Published: January 2005

AbstractThis paper reports the pattern of labeling in the cat superior colliculus produced by an antiserum raised against BSA‐conjugated gamma aminobutyric acid (GABA) and visualized by light and electron microscope immunocytochemistry. Neuropil labeling was densest within the zonal and superficial gray layers but was also found in the deep layers. Neurons labeled by the GABA antibody were also most dense within the zonal and superficial gray layers, although many labeled neurons were also found in the deeper layers. The ratio of labeled to unlabeled cells varied from an average of 45% in the superficial subdivision and the intermediate gray layer to less than 30% in the deeper laminae. Almost all intensely labeled cells were small (mean area = 127 μm2) and had varied morphologies.Several types of labeled cell were observed with the electron microscope. One type had a horizontal, fusiform cell body and a deeply invaginated nucleus. Another type had a small round or ovoid cell body with cytoplasm clumped at one end. Labeled cells with other morphologies were also occasionally seen. No labeled glial cells were found. Two types of vesicle‐containing dendrite were stained by the GABA antibody. One type had loose accumulations of small synaptic vesicles and often received input from retinal terminals. Another type had spines also containing small synaptic vesicles. Labeled dendrites without synaptic vesicles were also seen frequently. Putative axon terminals labeled by the GABA antibody had densely packed synaptic vesicles and formed symmetric synaptic contacts. Labeled myelinated axons were also commonly found.These results confirm those using uptake of tritiated GABA (Mize et al.: J. Comp. Neurol. 202:385‐396, '81, J. Comp. Neurol, 206:180‐192, '82) in that two of the same classes of GABA neuron, horizontal I and granule I cells, were identified in the superficial laminae. However, the GABA antiserum used in this study also revealed a third class of GABA neuron with vesicle‐containing spines. The antiserum also labeled a significant number of putative GABAergic neurons located in the deep subdivision of the cat superior colliculus which were not previously recognized by using transmitter autoradiography.
Putative glutamatergic and/or aspartatergic cells in the main and accessory olfactory bulbs of the rat
Authors: Fuller T. A. , Price J. L. 
Published: January 2005

AbstractThe “transmitter‐specific” retrograde axonal tracer 3H‐D‐asparate has been used to demonstrate neurons in the olfactory bulb which putatively utilize aspartate and/or glutamate as their neurotransmitter and which send an axon either to the piriform cortex or within the bulb itself.Injections of 3H‐D‐aspartate into layer I of the anterior piriform cortex, in the zone of termination of axons from the olfactory bulb, labeled only a few cells in the main olfactory bulb, located in the mitral and external plexiform layers. Although these cells resembled mitral and external plexiform layers. Although these cells resembled mitral and tufted cells, they tended to have smaller somata than other mitral or tufted cells and apparently form a distinct subpopulation of relay cells. In contrast, many of the mitral cells of the accessory olfactory bulb were labeled by the same injections of 3H‐D‐aspartate, probably as a result of involvement of the accessory olfactory tract or its bed nucleus in the injection site. Similar injections of the “nonspecific” tracer HRP into the anterior piriform cortex labeled most of the cells in the mitral cell layer of both the main and accessory olfactory bulbs, and some tufted cells in the external plexiform layer. It is concluded that only a small, distinct subpopulation of the mitral or tufted cells of the main olfactory bulb are aspartatergic and/or glutamatergic, while many (at least) of the mitral cells of the accessory olfactory bulb use the excitatory amino acids as transmitters.Injections of 3H‐D‐aspartate directly into the main olfactory bulb also failed to label the mitral and deeply situated tufted cells. However, a few cells were labeled in the periglomerular region, the superficial external plexiform layer, and the granule cell layer near the injection site. These labeled cells were smaller than mitral and tufted cells but generally larger than periglomerular or granule cells. They may represent a population of glutamatergic or aspartatergic short axon cells. In addition, small cells of an unknown type were labeled in the olfactory nerve layer following injections in the deepest part of the bulb. These cells do not correspond to any of the well characterized cell types of the olfactory bulb.