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O E Millhouse

Publications and source records attributed to O E Millhouse.

17 recordsLinked to original sources
PubMed1987

Granule cells of the olfactory tubercle and the question of the islands of Calleja.

The granule cell clusters in the rat olfactory tubercle were studied in Nissl-stained and Golgi-impregnated sections. Discrete cell clusters that vary in size and shape occur mainly in the multiform layer and less often in the molecular layer. In cell-stained sections they consist of small, round granule cells, 5-8 microns in diameter, that often surround a core or hilar area, which may contain larger neurons. In Golgi sections, the uni- or bipolar granule cells have a globular-shaped soma and varicose dendrites that are thin, have few branches, and are usually less than 100 microns long. The dendrites remain within the border of the cluster. There are few spines on most granule cells; however, a small population of granule cells is spine-rich. The axons are beaded, seldom have collaterals, and do not appear to exit from the cluster. Either in the hilus or in among granule cells are the special large hilar neurons, whose somata measure 15-17 x 18-22 microns. Unlike most of the neurons that are near a granule cell cluster, the dendrites, and perhaps axons, of the special large hilar neurons spread throughout a cluster. Differences in their dendrites suggest that there may be several varieties of them, but not enough examples have been studied to produce a useful classification. Some of their dendrites have bushlike terminal endings. Only the initial, beaded segment of their axons has been impregnated. Three types of afferent fibers have been identified: (1) Axons that are probably afferent to the olfactory tubercle course along a granule cell cluster giving off short collaterals that end in the periphery of a cluster. (2) Axon bundles that arise mainly from medium-sized densely spined neurons in the tubercle travel through a cluster, emitting boutons en passant or short collaterals that may end on granule cells. (3) Thick axons, which are among the thickest fibers in the olfactory tubercle, enter a cluster and develop a number of collaterals that in turn divide, and finally produce a unique terminal arborization in the cluster. The granule cell clusters are frequently identified as the islands of Calleja. A comparison of the structure of granule cells with that of the cells Calleja (La Region Olfactoria del Cerebro, Madrid: N. Moya, 1893) described in the "isolates olfativos," or islands of Calleja, indicates that he was pointing to the thickened, ruffled portions of the dense cell layer and not to the granule cell clusters.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Pallidal neurons in the rat.

The globus pallidus has been examined in rat brains with Golgi methods. Most of the impregnated cells, the typical pallidal neurons, have relatively large cell bodies and thick, infrequently branched dendrites that are several hundred microns long. Most dendrites have one or two spines, some of them are moderately spiny, and a few are quite spiny. Although the dendrites generally end by simply becoming thinner and beaded, they occasionally form special dendritic ramifications, which are similar to the complicated dendritic endings reported in primate brains. The variability in the size of the somata and in the structure of the dendrites is not sufficiently consistent to permit dividing the neurons into distinctive subsets. However, two forms of dendritic trees can be defined. The neurons in the center of the pallidum have radiate dendritic trees, whereas the cells along the borders have compressed dendritic trees. Two axonal patterns have been seen: ones with and ones without collaterals. All of the axons are beaded. Two other cell types were found. The special border cells along the external medullary lamina in caudal pallidum have dendrites that extend for some distance into the caudate-putamen. They otherwise resemble typical pallidal neurons. Small neurons that were infrequently impregnated may be interneurons, but their axons were not visualized. Their dendrites are short, varicose, and have a few spines. The spherical dendritic trees have a radius of 150-170 micron. Two sorts of axons that are probably afferent fibers were observed. The more common ones are nonbeaded, thin axons that have several boutons en passant and collaterals spaced along their length. In comparison, the other afferent fiber has numerous swellings, boutons en passant, and collaterals that are crowded together. They appear to invest the dendrites closely.

Afferent Pathways↗
PubMed1986

The intercalated cells of the amygdala.

The intercalated cell groups, or massa intercalata, of the amygdala have been studied in rodent brains with Golgi methods. They also have been examined in gallocyanin-chromalum-, AChE-, and Timm-stained rat brains. The Golgi data indicate that the intercalated cells are not confined to a series of isolated cell clumps but form a neuronal net that covers the rostral half of the lateral-basolateral nuclear complex, stretches across a major portion of rostral amygdala, and continues rostrally beneath the anterior commissure. There are two general types of intercalated neuron--medium and large neurons. The medium intercalated neurons are more common. They have round to elongate somata, 9-18 microns in diameter, and round to bipolar dendritic trees, depending on their location. Most of the dendrites are spine-bearing, as are 20% of the somata. Their axons often have locally ramifying collaterals. The parent axons apparently terminate in either the lateral-basolateral or central nuclei and some of them appear to enter the external capsule. There is a unique medium intercalated neuron that has nearly spine-free, varicose dendrites and an axon that is typical of short axon (Golgi II) cells. There are two varieties of large intercalated neuron-spiny and aspiny. Most of them are aspiny, although they usually have a few spines scattered along their dendrites. Both varieties have elongate, sometimes round, somata that can be as much as 60 microns long. Their dendrites are long, thick, and have few branch points. Only the initial part of the large aspiny cell axon has been impregnated. The large spiny cell axons have several local collaterals; the destination of the parent axons is unknown. The intercalated cells occur along fiber bundles, which are probably afferent to them. The axons that travel among the intercalated cells give off short collaterals and boutons en passant. The sources of these fibers are not known. From the published experimental data, it is likely that they originate in the piriform and entorhinal cortices, the lateral preoptic area, lateral hypothalamus, and ventral pallidum. Axon collaterals of basolateral nucleus pyramidal cells appear to terminate among the intercalated cells. It is suggested that the intercalated cells serve as sites for integration of the output of these various areas and, in turn, communicate it to the lateral-basolateral and central amygdaloid nuclei. The intercalated cells closely resemble neurons in the corpus striatum. Thus the question is raised and discussed of whether the intercalated cells are a ventral extension of the corpus striatum.

Acetylcholinesterase↗
PubMed1985

The connections between the basolateral and central amygdaloid nuclei.

With the use of the rapid Golgi method, axons that originate in the basolateral amygdaloid nucleus have been traced directly into the central amygdaloid nucleus in young mouse brains. The axons, which arise from pyramidal cells, have two patterns of collaterals within the central nucleus. In one type, the axon goes through the central nucleus toward the stria terminalis and emits only one or two collaterals. In the second type, the axon enters the central nucleus and gives off a number of thin collaterals, which have many boutons en passant along their course.

Amygdala↗
PubMed1985

The structure of the nucleus of the lateral olfactory tract.

The nucleus of the lateral olfactory tract (NLOT) was studied in rats with the rapid Golgi method. The nucleus is in the rostral part of the amygdala and has three distinct layers. Layer I is a superficial, fibrous layer; layer II, an intermediate, cell-dense layer; and layer III, a loosely textured cell and fiber layer. The commissural component of the stria terminalis forms at the apex of layer III. Layer II contains pyramidal and stellate cells; the former is more abundant. The apical dendrites of the pyramidal cells bow outward, point ventrally, and extend through layer I to the pial surface. The apical and basilar dendrites weave a dendrite capsule around layer II, except along its border with layer I. Most pyramidal cell axons go dorsally through layer III into the commissural component of the stria terminalis. The axons normally give off long, thin collaterals that travel rostrally into the forebrain. Other, shorter collaterals remain near the parent cell. Stellate cells have spine-poor dendrites that radiate throughout layers I and II. Their axons generate a dense terminal field that is confined to layer II. A special group of neurons, the border neurons, occur along the junction between layers I and II. Many of them look like modified pyramidal cells, and some look like horizontal cells. The axons of the latter ramify among the pyramidal cell apical bouquet dendrites in layer I. Along the perimeter of layer I, near the pial surface, are rounded cell bodies that have moderately spiny dendrites and axons that project dorsally. Layer III neurons are the largest cells in the NLOT. Three types of large cells were identified: large spiny neurons, large nonspiny neurons, and pyramidal cells, which were least common. The dendrites of all three neuron types reach beyond layer III into layer II or the adjacent anterior amygdala. Their axons were not followed far. They travel dorsally and give off a few collaterals, some of which enter layer II. Also in layer III, mainly in its apical region, are small nonspiny cells. Their dendrites and axons appear to be limited to layer III. The afferent fibers in layer I generally run parallel to the pial surface. They have a few short collaterals and boutons en passant. One afferent group in layer I is made up of thick axons that enter via the rostral edge of the layer.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1985

The zona incerta: another source of centrifugal fibers to the main olfactory bulb.

Neurons in the ipsilateral anteropolar division of the zona incerta were retrogradely labeled following injections of horseradish peroxidase in the main olfactory bulb. In addition, labeled cell bodies were found in the dorsal hypothalamus. Fewer and less densely labeled neuron cell bodies were seen in the contralateral zona incerta and dorsal hypothalamus. Most of the cells had a characteristic fusiform shaped soma, but a small number of the hypothalamic cells had spherical or conical shaped cell bodies.

Animals↗
PubMed1984

Cell configurations in the olfactory tubercle of the rat.

The rat olfactory tubercle was studied with the rapid Golgi method. Several distinct cell types were identified mainly on the basis of the size of their somata and the structure of their dendrites. The commonest neuron type in the tubercle is the medium-sized densely spined cell. The somata of these neurons occur chiefly in the dense cell and multiform layers. They also form the cell bridges that directly link the olfactory tubercle with the nucleus accumbens and caudate-putamen. Their dendritic trees exhibit a variety of shapes; some of them are spherical, some are bipolar, and others are asymmetrical. The axons project dorsally, deep into the multiform layer. En route they give off numerous collaterals. A large version of this cell type is the crescent cell. Other medium-sized neurons also have somata in the dense cell and multiform layers. They include the spindle cells, so named because of the shape of their cell bodies, and the medium-sized spine-poor neurons. Neither of these cell types has dendritic trees that are as highly branched as those of the medium-sized densely spined cells. There are three types of small cells; their somata occur primarily in the dense cell and molecular layers. The dwarf cells are near the pial surface, although their somata are included in the dense cell layer, and they have axons that resemble those of medium-sized densely spined cells. The radiate cells have numerous, relatively short, spine-free dendrites that extend out from the rounded somata in all directions. The small spine-rich cells look like miniature versions of the medium-sized densely spined neurons. They are frequently confined to the molecular layer. Large spine-poor neurons, with their cell bodies located in the dense cell and multiform layers, seem to be a heterogeneous cell group since there are subtle variations in the structure of their dendrites and the shape and extent of their dendritic trees. The large, moderately spined neurons are less common than the other large cells; their somata are found in all three layers. The granule cells of the islands of Calleja make up the most homogeneous cell group. They have only a few dendrites, and these are quite thin. Except for the medium-sized densely spined and dwarf cells, the axons of the different cell types were not very well impregnated. The different cell types in the tubercle are compared to cells in the nucleus accumbens, caudate-putamen, and globus pallidus.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1983

Neuronal configurations in lateral and basolateral amygdala.

The lateral and basolateral nuclei of the rat amygdala have been studied with the rapid Golgi method. Both nuclei have similar cell types, which closely resemble cells in the cerebral cortex. Therefore, we suggest that what is known about cortical circuitry can be used as a guide for studying synaptic circuitry in the lateral and basolateral nuclei. The most abundant neurons that are impregnated in both nuclei are pyramidal cells. They have conical cell bodies and easily recognizable apical and basilar dendrites. The ones in the center of each nucleus have long axes that roughly parallel the long axis of the nucleus. Towards the periphery, pyramidal cells have apical dendrites that either stick directly across the nucleus or follow along a nuclear border. The peripheral dendrites tend to enclose the nuclei. There is considerable overlap among the dendritic trees and the dendrites of one nucleus extend into the territory of the other. Pyramidal cells have extensive axonal systems. The principal axon of basolateral cells usually projects rostrally but long collaterals leave the nucleus in other directions. The axons of lateral nucleus pyramidal cells are also widely distributed. The major thrust of their axons is caudal and lateral. Stellate cells are the most common variety of the non-pyramidal cells. They occur in both nuclei and have round cell bodies, 10-15 micron diameter, and spherical dendritic trees that are confined to a limited region of the nucleus. Their axons form dense terminal fields that remain within the vicinity of the parent cell's dendritic tree. Another type of non-pyramidal cell is the cone cell, whose non-spiny, varicose dendrites describe cones. These neurons are found mainly in the apex of the lateral nucleus. The most rare non-pyramidal cells are the extended neurons, which have long, straight dendrites that reach beyond the nucleus into surrounding neuropil. They are mostly in the rostral part of the basolateral nucleus but also occur in the lateral nucleus, near the ventricular border. The axons of cone cells and the extended neurons have been only partially impregnated. We also have examined stellate cells in the guinea-pig lateral and basolateral nuclei. They have many of the same features as those in the rat brain, except that their dendritic trees and axonal systems are more complicated. There are two large groups of afferents: one consists of longitudinally running axons and the other of transversely coursing fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1978

Cytological observations on the ventromedial hypothalamic nucleus.

Two sorts of neurons are recognized in Golgi impregnations of the rat ventromedial hypothalamic nucleus (HVM). The two cell types, category I and II neurons, are differentiated on the basis of their somatic, dendritic, and axonal characteristics. Category I neurons form most of the neuronal population and are located throughout HVM. The small number of category II neurons that have been studied occur in lateral HVM. Two varieties of neuronal profile, "common" and "uncommon cells", are seen in thin sections of HVM. The "uncommon cells", in comparison with the "common ones", appear to have a larger soma, a more electron-dense cytoplasmic matrix, an abundance of Nissl bodies, and a population of dense-cored vesicles (100--130 nm in diameter). Some of the somata and proximal dendrites of "common", but not "uncommon" cells, are wrapped in multiple layers of astrocytic processes. Although the correlation is tentative, it is argued that category I neurons correspond to "common cells" and category II, to "uncommon cells". One possible implication of this correspondence is discussed regarding neuronal alteration in response to change in the endocrinological environment of the brain.

Animals↗
PubMed1976

Ultrastructure of the Gunn rat substantia nigra I. Cytoplasmic changes.

The substantia nigra of various aged hyperbilirubinemic (Gunn) rats was studied by means of electron microscopy. The cytological features observed in the neuronal somata were the presence of (1) complex membranous bodies (CMBs), (2) dilated cisternae of granular endoplasmic reticulum, (3) single membrane bound vacuoles and (4) enlarged mitochondria. Nearly every neuronal soma studied in two week old Gunn rats contained CMBs, which consisted of several layers of membrane that usually, but not always surrounded small islands of cytoplasm. On occasion CMBs were seen to be directly connected with granular endoplasmic reticulum and, in a few instances, they were located within a cistern of endoplasmic reticulum. There were significantly fewer CMBs in the neuronal somata of adult Gunn rats. They were located peripherally in the somata or in the proximal portions of dendrites. Furthermore, in these animals the cytoplasm appeared normal and did not exhibit the features commonly seen in younger animals. Only a few hyperchromatic neurons were observed and no pronounced gliosis was evident. Therefore it is assumed that the majority of substantia nigra neurons recovered from the toxic effect of bilirubin or that the concentration of bilirubin deposited in the substantia nigra is not sufficient to be lethal. The hypothesis that is considered is that CMBs represent autophagic activity which results from exposure of neurons to bilirubin. The adjacent neurites and glia did not demonstrate the cytoplasmic changes that were characteristic of the neuronal somata.

Age Factors↗
PubMed1976

Ultrastructure of the Gunn rat substantia nigra. II. Mitochondrial changes.

The substantia nigra of hyperbilirubinemic (Gunn) rats was studied using light and electron microscopic techniques. PAS-positive inclusions were observed within the neuronal somata of animals 2 to 12 weeks old. Incubation of tissue sections in 0.5% diastase inhibited most of the positive PAS reaction, thus indicating the intraneuronal presence of glycogen. Electron microscopic examination of the tissue substantiated the histochemical data. Mitochondria in neuronal somata contained collections of osmiophilic granules, 200-300 A diameter, in their intracristal (intermembrane) space. These granules were typical of beta-glycogen particles. In increasingly older animals (from 2 to 12 weeks old) progressively fewer collections of intramitochondrial glycogen were observed. In these same animals there was, however, a concomitant increase of osmiophilic granules, 400-600 A diameter, located in the cisternae of granular endoplasmic reticulum. These granules corresponded to alpha-glycogen. After 12 weeks of age, only occasional glycogen granules were seen in either the mitochondria or endoplasmic reticulum. It is suggested that the intramitochondrial glycogen represents an alternate means by which the neuron is able to manufacture ATP following the disruption of oxydative phosphorylation caused by bilirubin. Furthermore it is suggested that with the recovery of oxydative phosphorylation the intramitochondrial collections of glycogen are transferred to the endoplasmic reticulum where glycogenolysis might possibly occur.

Age Factors↗