bluuebunny/crossref_metadata_2025 huggingface dataset:
Number and distribution of the apical dendritic spines of the layer V pyramidal cells in man
Authors: Marin‐Padilla Miguel
Published: January 2005

The number and the distribution of the apical dendritic spines was investigated in the layer V pyramidal cells of the human cerebral cortex. This study was carried out in the motor cortices of an 8‐month fetus, a premature infant, and a newborn, 15‐, 19‐ and 45‐day‐old infants; in the somesthetic cortex of a newborn infant; and in the auditory cortex of a newborn infant. This study has shown: (a) that the number of spines increases with the age, (b) that the spines are distributed along the apical dendrites in a characteristic manner which, graphically represented, consists of a curve with three distinct deflexions, (c) that the spine‐distribution along the apical dendrites of the layer V pyramidal cells is similar in all cases studied regardless of their age or their cortical location (motor, somesthetic and auditory cortices), (d) that the distribution of the spines along the apical dendrites appears to depend on the nature of the dendrite, (e) that the sequence of the mean number of spines maintains an exponential relationship with the distance from the cell body for the first and second deflexions of the spine‐distribution curves. The significance of the distribution of the spines along the apical dendrites of the layer V pyramidal cells is discussed. A new method is presented and its possible application to the study of the normal development and pathoIogical conditions of the cerebra1 cortex is suggested.
The hyperstriatal region of the avian forebrain: A lesion study of possible functions, including its role in cardiac and respiratory conditioning
Authors: Cohen David H.
Published: January 2005

The behavior of 12 pigeons with hyperstriatal lesions (10 bilateral and 2 unilateral) was compared with that of 13 control birds. Neurological examination indicated no striking postural deficits, and all reflexes investigated were normal. However, lesions did reduce escape behavior, spontaneous flight, and responsiveness to exteroceptive stimuli. Avariety of vegetative functions including body temperature, food and water intake, and cardiac and respiratory rate were unaffected.

Defensive conditioning, differentiation and extinction performance were also assessed. Birds with lesions showed no impairment of cardiac conditioning, but respiratory conditioning was slower than in control animals. Both cardiac and respiratory differentiation were weak, respiratory differentiation being more severely affected than cardiac differentiation. Neither group of birds showed extinction.

Evidence for hpyerstriatal participation in visual function is reivewed, and it is proposed that an important role of the hyperstriatum is mediation of certain somatic responses to visual stimuli and that deficits following ablation may be secondary to impairment of visual orienting responses.
Marsupial interhemispheric relation
Authors: Putnam Serpas J. , Megirian David , Manning John W.
Published: January 2005

Three different responses recorded from the opossum neocortex following a stimulus to the homotopical point on the contralateral hemisphere were: the interhemispheric early response (IER), the interhemispheric delayed response (IDR), and the rhythmic afterdischarge (RA). The IER was a short latency biphasic slow wave evoked potential which could be recorded from every homotopic point on the neopallium with the exception of a part of the striate cortex. Each active homotopic point had a limited heterotopic halo. The homotopic positive peak latency varied from 5.3 msec in the area parietalis to 14.7 msec in the area striata. Interhemispheric transfer was effected via the anterior commissure. The IDR was a late slow wave evoked potential and had an extensive heterotopic representation. This potential could be recorded in the contralateral hemisphere after sectioning the anterior commissure. The homotopic positive peak latency varied from 60.2 msec in the area parietalis to 76.1 msec in area striata. To abolish the IDR both the di‐mesencephalic junction and the interthalamic commissure had to be sectioned. The RA is a very labile late oscillatory potential which was very difficult to demonstrate without a computer of average transients. The pattern of its homotopic and heterotopic representation resembled very closely that of the IER. Under the conditions of our experiment it had a negative peak latency of 224–230 msec, a frequency of oscillation of three seconds and a maximum duration of 2.2 seconds. To abolish the RA both the di‐mesencephalic junction and the interthalamic commissure had to be sectioned. The dorsal commissure contained no neopallial intorhemispheric fibers. The anterior commissure carried these commissural connections. The two late responses reported in the opossum fell within the general context of mammalian late responses.
Developmental changes of the endoplasmic reticulum and ribosomes in nerve cells of the spinal ganglia of the domestic fowl,
Authors: Pannese Ennio
Published: January 2005

The changes of the endoplasmic reticulum (ER) and ribosomes in developing nerve cells of the spinal ganglia of the domestic fowl have been studied by light and electron microscopy.

The thin rim of cytoplasm encircling the nucleus of the undifferentiated cells contains numerous free ribosomal clusters and a scanty endoplasmic reticulum.

The primitive neuroblasts are spindle‐shaped and their two processes contain filamentous structures. In comparison with the undifferentiated cells, primitive neuroblasts have many more free ribosomes and a prominent rough‐surfaced ER consisting of long, interconnected channels often continuous with the nuclear envelope. The remarkable development of the ER is one of the main characteristics of differentiating ganglionic nerve cells. Subsurface cisternae become apparent first in the primitive neuroblasts.

The ER and ribosomes of the intermediate neuroblast are confined in the peripheral region of the perikaryon; mitochondria, Golgi complexes, dense bodies, microtubules, neurofilaments, etc. are located more centrally. Units of the smooth‐surfaced ER appear first in the intermediate neuroblasts.

In the pseudo‐unipolar nerve cells, the cisternae of the ER and the ribosomes are mainly grouped in discrete areas (Nissl bodies). The rough‐surfaced ER is more developed and highly organized in the intermediate neuroblasts and especially in the pseudo‐unipolar nerve cells than in the primitive neuroblasts. In the pseudo‐unipolar nerve cells, peculiar relationships between ER and Golgi complexes have been observed.

Both free and membrane‐attached ribosomes are arranged in clusters (polysomes) in all the developmental stages of the ganglionic nerve cells. The highest number of ribosomes in the membrane‐attached polysomes is at least 13.

The electron microscopic images suggest that the ER of the developing neuroblasts might take its origin from the nuclear envelope and afterwards might increase in volume through an intrinsic expansive growth of its membranes.
A secretory role for the lipid bodies of molluscan neurons
Authors: Benjamin P. R. , Peat A.
Published: January 2005

The lipid bodies of neurons from the osphradia ganglion of the freshwater Snail Planorbarius corneus have been examined with the electron microscope. These lipid bodies show a variety of structural forms which have been interpreted as a cycle. Early stages consist of a single‐membraned sac enclosing cytoplasm similar in appearance to that of the general neuronal cytoplasm. Complicated systems of membrane lamellae and filaments develop with the membranes often being associated with oval areas of structureless material. The later stages of the cycle are dominated by this material. It seems probable that the structureless material is secreted by the membranes. The lipid bodies show a breakdown sequence when their contents pass into the neuronal cytoplasm. Remnant lipid bodies have been found which contain only fragments of membrane and a small number of filaments, with small areas of residual structureless material. A possible neurosecretory role is considered.
An electron microscopic study of the neuroglia during postnatal development of the rat cerebrum
Authors: Caley David W. , Maxwell David S.
Published: January 2005

The differentiation of spongioblasts from undifferentiated cells and into neuroglial cells has been studied in the postnatal rat cerebral cortex with the electron microscope. The nuclei of all the non‐neural elements are characterized by clumping of dense chromatin, especially near the nuclear envelope. The undifferentiated cells possess only a thin rim of perinuclear cytoplasm containing few organelles. Spongioblasts are characterized by an increased number of cytoplasmic organelles, mostly mitochondria and Golgi complex, and by the growth of processes. These cells mature and take on either the features of oligodendrocytes or astrocytes. The multiple oligodendrocyte processes are thin and branching and develop intimate contacts with the developing axons. Early stages of myelination are characterized by the envelopment of axons by oligodendrocyte processes which overlap each other to form inner and outer tongues that are cheracteristic of central nervous system myelin. Astrocytes can be distinguished by the presence of cytoplasmic glycogen particles and fibrils. Processes of these latter cells develop intimate relations with the developing blood vessels. A variety of cell was occasionally encountered which is termed the polycystic cell. This cell may be quite large, contains numerous cysts and vesicles of various types and appears to be a form of spongioblast. No cells which would qualify as “microglia” were observed.
The aorticorenal ganglion and its role in renal innervation
Authors: Norvell John E.
Published: January 2005

A detailed dissection of the renal plexus and the aorticorenal area was carried out in 57 adult cadavers (32 males and 25 females). This study showed that the aorticorenal ganglia may be located anywhere in the general area of the junction of the renal arteries with the aorta. These ganglia were found to be partly fused with the celiac ganglion in 4% on the right side and in 12% on the left. All three thoracic splanchnic nerves (greater, lesser, and least) may have rami which terminate in the aorticorenal ganglia. The least splanchnic terminated in the aorticorenal ganglion more often than the other nerves when the ganglion was located inferior to the renal artery. In this location, the first lumbar splanchnic nerve also may terminate in the aorticorenal ganglion. The aorticorenal ganglia also had connections with the renal plexus, inermesenteric nerves, celiac and superior mesenteric plexuses, adrenal gland, and possibly with the spermatic and ovarian plexuses through the renal plexus.

By using the silver impregnation technique of Holmes, we found the aorticorenal ganglia to have a role in renal innervation. When these ganglia were unilaterally removed from a series of 14 cats, a definite reduction of nerve fibers associated with the tubules of the renal cortex, and to lesser extent, with the renal blood vessels, was observed. Most nerve endings were associated with the proximal convoluted tubules, but a few were observed in the glomeruli.
Golgi study of the nucleus of the transpeduncular tract in the rabbit
Authors: Giolli Roland A. , Braithwaite J. Ronald , Streeter Thomas T.
Published: January 2005

The nucleus of the transpeduncular tract was studied in Golgi, reduced silver, and Nissl series of the brain stems of newborn and adult albino rabbits. The nucleus contains cells which differ with respect to their dendritic orientation, dendritic pattern, and size. The terms intranuclear and extranuclear are further used to designate those cells respectively whose axons are restricted to the nucleus or are projected outside the nucleus. The intranuclear cells usually lie ventrally, and their axons distribute dorsally, within the nucleus; and on this basis, the nucleus is divisible into ventral and dorsal divisions. The axons of some of the extranuclear cells studied project and terminate within the substantia nigra, midbrain reticular formation, or red nucleus; whereas the axons of others pass into the transpeduncular tract or medial lemniscus.

This study reveals that individual axons of the transpeduncular tract terminate in ventral or dorsal nuclear divisions and suggests that the transpeduncular tract input comprises the largest projection to the nucleus. Axons of cells of the substantia nigra, as well as axons passing from the midbrain reticular formation and probably the anterior accessory optic tract, are shown to terminate primarily within the dorsal division of the nucleus. Axons from the cerebral peduncle are found to end mainly within the ventral division of the nucleus. The findings are discussed in relation to existing biological data.
Calibre spectra of the lingual and hypoglossal nerves of the rhesus monkey
Authors: Egel Robert T. , Bowman James P. , Combs C. Murphy
Published: January 2005

The presence of muscle spindles in the tongue of the rhesus monkey and their absence in the cat's tongue, raises the question of whether this difference alters the structural and functional composition of, in particular, the rhesus monkey's hypoglossal nerve as compared to the same nerve in the cat. Using both random and complete sampling techniques, calibre spectra analyses were carried out on the following regions of the rhesus monkey's hypoglossal nerve: The medial and lateral end branches, and regions of the main trunk proximal and distal to the point where the ramus descendens is given off. In addition, the calibre spectrum of the lingual nerve was determined. The results suggested that neither the lingual nerve nor the proximal region of the hypoglossal nerve contained enough fibers of Group I diameter to justify the statement that they cintained spindle afferents. Distal to the point where the cervical contribution joins the hypoglossal nerve, however, the calibre spectrum exhibited a marked shift towards a closer resemblance to the spectra of limb muscle nerves in terms of the proportion of Group I diameter fibers. These findings suggested that although lingual spindle afferent fibers are present in the distal portion of the monkey's twelfth nerve, they may not reach the central nervous system in this nerve.
Cerebellar cortex of rat and other animals. A structural and ultrastructural study
Authors: O'Leary James L. , Petty Jerry , Smith Jeanne M. , O'Leary Mary , Inukai Joseph
Published: January 2005

Cerebellar cortex was studied in 100 rats and other animals, 15–30 days old, using Golgi, intravitam methylene blue, and ultrastructural methods. Marchi and Nauta provided certain controls. Degeneration of afferent terminals was sought following lesions of pons and olive.

In normal material, emphasis was upon the changing field relations between folial summit, side wall, and sulcus, Many previous findings of Fox, Ramon y Cajal and Snider were confirmed, and the effort made to reconcile departures from characteristic axonal and dendritic configuration with cytoarchitectonic pattern.

Mossy and climbing terminals were examined in normal and degenerated states, using Golgi and ultrastructural material. Climbing fibers in Golgi are described in detail, including variations in course and sites of branchings. Mossy degeneration was found 3–5 days after lesions of both pons and olive. The clearest evidence thereof was provided in ultrastructural material. Minor evidences of degeneration were also found in climbing fiber strands in both materials, but on gross degeneration was encountered. Corresponding Golgi material was used for visualizing intact fibers in the face of adequate lesions.

Ultrastructure also provided evidence concerning the axon cap surround, the initial segment of the Purkinje axon, Comparison with these segmests in other cell types, and cross‐identification of synapses between axon types and the different cell profiles of Golgi material.
Distribution of monoamine‐containing nerve terminals in the brain of the painted turtle, Chrysemys picta
Authors: Parent A.
Published: January 2005

The distribution of monoamine (catecholamines and 5‐hydroxytryptamine)‐containing nerve terminals in the brain of the painted turtle (Chrysemys picta) was studied by means of the histofluorescence technique of Falck and Hillarp. The highest concentration of monoamine terminals in this reptilian brain occurs within the ventral region of the strio‐amygdaloid complex which on this basis may be related to the mammalian neostriatum (caudate nucleus and putamen). Numerous catecholamine type nerve endings are also present in several other regions of the turtle brain, namely: the dorsal cortical layer, the dorsolateral portion of the septum, the habenula, the nuclei dorsomedialis and dorsolateralis of the thalamus, the lateral part and median eminence of the hypothalamus, the tectum and the brain stem reticular formation (more especially its lateral edge). The greatest concentration of 5‐hydroxytryptamine (serotonin) type nerve endings is found in the dorsomedial portion of the septum, nucleus geniculatus lateralis, nuclei pretectalis, interpeduncularis and isthmi, the tectum and the reticular formation of the brain stem (more especially its medial portion). These monoamine nerve terminals belong to several groups of neurons whose cell bodies are located in the brain stem and, to a lesser degree, in the hypothalamus of the turtle.
The structure of the medial geniculate nucleus (MGN): A cyto‐ and myeloarchitectonic study in the squirrel monkey
Authors: Jordan Hans
Published: January 2005

The cyto‐ and myeloarchitectonic organization of the Medial Geniculate Nucleus (MGN) were investigated by means of several histological series sectioned in different planes. Eight hemispheres of normal adult monkeys (Saimiri sciureus) were used. The shape of the nucleus and its anatomical relationships to the surrounding structures were established. The MGN is ovoidshaped, forming a slight prominence at the ventrolateral surface of the brain. It is separated from the Lateral Geniculate Nucleus (LGN) by a capsule of myelinated fibers which surrounds the lateral and ventrocaudal aspects of the nucleus. The medial boundaries with the thalamic structures are difficult to determine.

Three subdivisions of the nucleus were identified and their spatial interrelationships were determined: MGNa being composed of small irregularly shaped cells, MGNb containing both pale medium‐sized and large scattered multipolar nerve cells and MGNc with densely packed, medium‐sized and ovoid nerve cells.

MGNa is located in the ventrocaudal portion of the nucleus, MGNb occupies most of the medial extent of MGN being laterally adjacent to MGNc.
Investigation of glial cells in semithin sections. III. Transformation of subependymal cells into glial cells, as shown by radioautography after 3H‐thymidine injection into the lateral ventricle of the brain of young rats
Authors: Paterson Jean A. , Privat A. , Ling E. A. , Leblond C. P.
Published: January 2005

Strong labeling of the cells in the subependymal layer was produced by stereotaxic injection of 5 μCi of 3H‐thymidine into the left lateral ventricle of the brain of one and a quarter month old rats weighing about 100 gm. These animals were sacrificed by glutaraldehyde perfusion from two hours to 21 days later. Blocks of corpus callosum with adjacent subependymal and ependymal layers were excised from the injected and non‐injected sides, and embedded in Epon; 0.5 μ thick sections were radioautographed and stained with toluidine blue.

In the subependymal region, on both injected and non‐injected sides, there was an immediate uptake of label by many cells followed by an increase and later a decrease in the percent cells labeled. In the corpus callosum while at first the percent labeling of glial cells was rather low, it did increase slowly with time and, after seven days, exceeded that in the subependymal region. These results were interpreted as indicating that cells arising in the subependymal layer had migrated into the corpus callosum.

Up to four days after injection, most of the label in corpus callosum was present in immature‐looking cells resembling the cells of the subependymal layer and referred to as free subependymal cells. With time, the percent labeling decreased in these cells while increasing in some of the glial cells. A labeling peak was observed for light oligodendrocytes at four to seven days and for dark oligodendrocytes at 21 days, whereas labeling of medium shade oligodendrocytes occurred at intermediate times. The succession of labeling peaks indicated a sequence of development from free subependymal cells through light and medium shade to dark oligodendrocytes. Few astrocytes carried label at any time; those which did seemed to have arisen from the transformation of labeled free subependymal cells. Microglia were unlabeled at two hours, but their percent labeling was high at 4–14 days. While the labeling of other glial cells reflected their physiological behavior, the labeling of microglia was a consequence of the trauma produced by the injection 0f tracer into the ventricle.

In conclusion, cells coming from the subependymal layer appear to migrate into the corpus callosum where, in 100 gm rats, many of them transform into oligodendrocytes and a few into astrocytes.
Stereological description of the anterior horn cervical cord of the adult rat. A quantitative study using the optical microscope
Authors: Mayhew T. M. , Momoh C. K.
Published: January 2005

The histometric properties of the most ventral, ventromedial and ventrolateral zones in the anterior horn of adult rat cervical enlargement were studied by quantitative optical microscopy. The spinal cord areas were identified in semi‐thin Araldite sections and unbiased samples of the test tissue were recorded on photomicrographs. By defining the tissue on the basis of a histometric model, it was possible to describe a number of important stereological parameters including compartmental volume proportions, cellular packing densities, perikaryal volumes and surface areas, and blood vessel length per unit volume.

It was established that each cubic milimetre of tissue consists of approximately 0.85 mm3 of neuropil, 0.04 mm3 of blood vessels, 0.02 mm3 of neuroglial cells, 0.08 mm3 of motoneuron perikarya and 0.02 mm3 of small neuron perikarya. Roughly 0.11 mm3 of the neuropil compartment can be attributed to myelin. Estimates of cell body packing densities revealed an average of 44,950 neuroglial cells and 11,650 neurons per mm3. Small and motor neurons occur in approximately equal numbers. The average motoneuron has a perikaryal volume of 12,100 μm3 and a perikaryal surface area of 2,500 μm2. Corresponding figures for small neurons are 2,200 μm3 and 650 μm2. The average glial cell soma has a volume of 370 μm3. Differences between the nuclear volume proportions and nuclear size distributions of glial cells, small neurons and motoneurons are also reported. Each mm3 of tissue contains 1.2 metres of blood vessels, of average diameter 6.4 μm and with an outer surface area of 21 mm2.

The results are presented and discussed in the context of data published by workers in other laboratories.
Reconstruction of axonal trajectory of individual neurons in the spinal cord using Golgi‐stained serial sections
Authors: Mannen Hajime
Published: January 2005

A procedure bringing the axonal and dendritic cut ends found in the confronting planes of the serial sections face to face by means of serial photomicrographs provides a means for precisely reconstructing individual Golgiimpregnated neurons. Utilizing this method, it was possible to follow at the caudal level of a kitten's spinal cord the total course of the axons and dendrites of sixteen intramedullary neurons.

The neurons located in the dorsal horn (lamine IV and V) send their long ascending axon into the lateral funiculus of the ipsi‐ or contralateral side, and, in one case, into the anterior funiculus of the ipsilateral side, giving off on the way several collateral to the dorsal half of lamina VII of the ipsi‐ or contralateral side. Some of the neurons found in the intermediate region and the ventral horn (laminae VII, VIII and X) distribute their axonal branches in the intermediate region or the ventral horn of the ipsi‐ or contralateral side or both sides, running throughout their course in the grey matter, while the others act in the same manner by way of the lateral or anterior funiculi. Axonal and collateral endings terminate with small terminal knobs. The total axonal length of the neurons observed, with the exception of some with a long ascending trajectory, varies from 1,680 μm to 6,480 μm.
Retrograde axonal transport of horseradish peroxidase in peripheral autonomic nerves
Authors: Ellison Jeffrey P. , Clark G. Michael
Published: January 2005

An exogeneous marker protein, horseradish peroxidase (HRP) was used to trace peripheral autonomic pathways in adult guinea pigs and cats. Small doses of HRP were injected into various organs and after a brief survival period, HRP activity appeared in the perikarya of autonomic neurons that supplied each injection site. After injection of HRP into the anterior chamber of the eye, reaction product was detected in the postganglionic sympathetic neurons of the superior cervical sympathetic ganglion. In another experiment, HRP reaction product was found in the cell bodies of the preganglionic sympathetic neurons that supply the adrenal medulla. These were located in the lateral gray column of the spinal cord at T6 and T7 segmental levels. Reaction product appeared in intramural postganglionic parasympathetic neurons close to an injection site in the wall of the urinary bladder and in a similar situation in Meissner's ganglia of the ileum. Following injection into the walls of the stomach and ileum, HRP labelled cells were detected in the nodose ganglion of the vagus and in preganglionic parasympathetic neurons in the dorsal motor nucleus of this nerve. After injection into the subepicardial tissue of the heart, reaction product appeared in the stellate ganglion and also in an upper thoracic dorsal root ganglion. These data suggest that HRP is taken up by peripheral autonomic nerves of all types, and then undergoes rapid retrograde axonal transport to the perikaryon. It appears, therefore, that HRP may be useful in tracing both motor and sensory peripheral autonomic pathways.
Late ultrastructural changes in neuronal mitochondria after lonizing radiation of the brain
Authors: Samorajski T.
Published: January 2005

Brain tissue was examined for morphological changes at 12 and 16 months after focal irradiation of the brain in female mice. Irradiation was performed with deuteron beams derived from the 60‐inch Brookhaven cyclotron at a rate of 1925 rad second−1 through an anti‐Bragg device which produced uniform exposure. Experimental animals received a dose of 10,000 rad, covering a 9 × 5 mm area over the skull and extending into the brain for a depth of about 2 mm. An additional group of animals served as sham‐irradiated controls. Histological studies revealed extensive cell loss, vacuolation, and prominent vascular changes in irradiated regions of the brain at 16 months postirradiation. Ultrastructural examination of brain tissue at 12 and 16 months after irradiation revealed the presence of unusual elongated mitochondria with parallel arrays of cristae. Altered mitochondria were more prevalent at the longer post‐irradiation interval.
On the absence of a rubrothalamic projection in theb monkey with observations on some ascending mesencephalic projection
Authors: Hopkins David A. , Lawrence Donald G.
Published: January 2005

In order to determine whether there is a rubrothalamic projection in the rhesus monkey, the ascending degeneration resulting from electrolytic lesions made in the red nucleus and adjacent mesencephalon in animals surviving at least one year after bilateral interruption of the superior cerebellar peduncles (PCS) was studied by means of the Fink‐Heimer technique. In a necessary preliminary step it was shown that virtually all of the degeneration disappeared from the thalamus within twelve months after PCS interruption so that degeneration resulting from the subsequent electrolytic mesencephalic lesions could be attributed to interruption of non‐cerebellascending fibres.

The results show that degeneration was present in the thalamus following the electrolytic mesencephalic‐diencephalic lesions but it could be accounted for on the basis of damage either to residual PCS fibres, to somatosensory pathways, to intrathalamic connections or to cell groups or projection fibres of the reticular formation, substantia nigra of globus pallidus. It is concluded that there is no direct rubrothalamic projection in the monkey and, in particular, no evidence of a projection from the red nucleus to the ventral lateral of ventral anterior thalamic nuclei.

The results also indicate that the mesencephalic reticular formation is the main source of ascending afferents to the nucleus reticularis thalami. Some observations were made concerning nigrostriatal and nigrothalamic projections.

Retrograde cell changes resulting from unilateral lesions made caudal to the red nucleus were studied in three animals. The observed cell changes are interpreted as being consistent with the conclusion that there is no rubrothalamic projection.
An estimate of the number of cells arising by division in mouse cerebral hemispheres from age one to 12 months: An autoradiographic study of DNA synthesis
Authors: Mareš Vladislav , Lodin ZdeněK , Jílek Miloš
Published: January 2005

Male CBA strain mice aged 1, 2, 4, 6, 8 and 12 months were injected with 5 μCi of 6‐H3‐thymidine per gm body weight and killed two hours after the injection. Incorporation of the isotope, as a measure of DNA synthesis and cell division, was studied in the cerebral cortex and corpus callosum by light‐microscope autoradiography. DNA synthesis was found in a small number of nuclei of non‐neuronal cells, both of ecto‐ and mesodermal origin. The percentage of labeled cells (Labeling Index, or LI) decreased in both regions exponentially with age. On the base of measured LI values, the total number of cells arising from age one to 12 months was calculated. As the reference value the number of cells in one month‐old animals was taken. The calculated cell increment in the ectodermal population in the cortex amounted to 19.7–20.6% (average 20.2%) and to 196.0–425.0% (average 247.0%) in the corpus callosum (pairs of figures correspond to values calculated from LI values measured in sagittal and frontal sections). When all labeled cells (LC) were taken into consideration (of both ecto‐ and mesodermal origin) the corresponding cell increment ranged from 25.0–30.5% (average 26.8%) in the cortex and from 205.0–454.8% (average 263.0%) in the corpus callosum. The number of all newly arising cells in the whole hemisphere (including both cerebral cortex and corpus calosum) calculated from mean LI values of all LC in sagital and frontal sections amounted to 52.0%.

It is suggested that the observed DNA synthesis and cell division, particularly in the corpus callosum and mesodermal cell groups of both regions studied, correspond mainly to renewal of cell populations. In the cerebral cortex accumulation of some newly arising cells in situ cannot be excluded.
Cerebellar cortical efferents of the posterior lobe vermis in a prosimian primate (Galago) and the tree shrew (Tupaia)
Authors: Haines Duane E.
Published: January 2005

The topographical organization of cerebellar cortical efferents of the posterior lobe vermis was studied in a prosimian primate (Galago senegalensis) and the tree shrew (Tupaia glis). Two patterns emerge; one which shows longitudinal zones of the entire vermis and a second which shows that individual lobules within the overall longitudinal pattern terminate in specific areas of the ipsilateral medial cerebellar nucleus (NM) and vestibular complex.

The posterior lobe vermis consists of a narrow midline portion which projects bilaterally into the NM and a paramidline zone which projects only into the ipsilateral NM. These two zones are probably comparable to, and subdivisions of, Zone A of Voogd ('69). The lateral vermal zone projects primarily into the ipsilateral vestibular complex and/or interposed nuclei and appears to correspond to Zone B of Voogd ('69). Within this overall pattern individual lobules project into specific portions of the NM. From rostral to caudal (lobules VI to IX) terminal fields in the NM shift from dorsal and dorsomedial to ventral and ventrolateral. This is the inverse of the pattern of termination seen in the vestibular complex from lesions of the same lobules where from rostral to caudal (VI to IX) there are overlapping terminal fields from lateral to medial. With the exception of the narrow midline zone cerebellar corticonuclear projections of the posterior lobe vermis are ipsilateral. There is a more complex and more precise relationship between the posterior lobe vermis, NM and vestibular complex than previously suggested.
Different targets of different neurons in nucleus gracilis of the cat
Authors: Berkley K. J.
Published: January 2005

Efferent projections of neurons in the cat nucleus gracilis to the ventrobasal complex (VB) of the thalamus and the dorsal accessory portion of the inferior olive (IOd) were studied using tracing techniques that exploit neuronal orthograde and retrograde intra‐axonal transport processes. These projections were studied in order to determine if the heterogeneity of the morphology, physiology and afferent input of the nucleus gracilis is paralleled by a similar heterogeneity in its efferent projections.

In an orthograde study, 3H‐leucine and/or 3H‐proline were injected into the nucleus gracilis of different subjects in an attempt to label different proportions of large (>18 μ) and small cells. This procedure permitted study of the efferent targets of the two cell types. The amount of labeling in VB was a constant ratio of the number of large cells in the nucleus gracilis that had incorporated the isotope. This relationship was not observed for the small cells. The amount of labeling in IOd was dependent neither on the number of large nor the number of small cells that had incorporated the isotope.

In a retrograde study following extensive injections of horseradish peroxidase (HRP) into the thalamus, only large cells (>18 μ) in the dorsal column nuclei were filled with HRP reaction product. These cells were located predominantly in clusters in the middle zone of the nucleus gracilis as well as rostrally. After injections including (but not confined to) the inferior olive, small cells located in the rostral and middle zones were filled with reaction product. A few large cells located ventrally in the middle zone of the nucleus gracilis and rostrally were also filled. Some of these ventrally located large cells may project in a collateral fashion both to the thalamus and to the inferior olive.

The results of both the orthograde and retrograde studies are consistent with other evidence on the heterogeneity of the nucleus gracilis. These data strongly support the conclusion that the population of cells in the nucleus gracilis that projects to the thalamus overlaps with but is not identical to the population of cells that projects to the inferior olive.
Retinofugal pathways in the longnose gar Lepisosteus osseus (linnaeus)
Authors: Northcutt R. Glenn , Butler Ann B.
Published: January 2005

Retinal projections were studied with autoradiographic and silver methods in the gar, Lepisosteus osseus, one of the two surviving members of the holostean actinopterygians. Contralaterally, the retina projects to the preoptic nucleus of the hypothalamus, and, via the medial optic tract, to the dorsal thalamus, medial ventral thalamic nucleus, nucleus pretectalis profundus pars ventralis and pars dorsalis, and the medial portion of the deep layer of the central zone in the optic tectum. The dorsal optic tract projects to the lateral ventral thalamic nucleus, nucleus pretectalis centralis, and the superficial white and gray zone of the optic tectum. The ventral optic tract terminates in the nucleus of the ventral optic tract, the lateral and medial ventral thalamic nuclei, nucleus pretectalis superficialis, nucleus pretectalis centralis, nucleus pretectalis profundus pars ventralis, the basal optic nucleus, and the superficial white and gray zone of the optic tectum. Ipsilateral projections are to similar sites, except for an absence of inputs to the lateral ventral thalamic nucleus from the dorsal tract and to the nucleus pretectalis superficialis, nucleus pretectalis profundus pars ventralis, and the basal optic nucleus from the ventral tract. The presence of ipsilateral retinal projections in gars is compared to their presumed absence in teleosts, and comparisons of retino‐recipient targets in gars are made with teleosts and with non‐actinopterygian vertebrates.
Organization of the tectofugal visual pathway in the pigeon: A retrograde transport study
Authors: Benowitz Larry I. , Karten Harvey J.
Published: January 2005

In birds, superficial laminae of the optic tectum receive a massive retinal input; the tectum in turn projects upon the nucleus rotundus thalami, which then sends its efferents to the ectostriatal core of the telencephalon. To examine the detailed organization of this principal ascending visual pathway, small injections of the marker horseradish peroxidase (HRP) were placed in various sites throughout the ectostriatum (E) or nucleus rotundus (Rt) in pigeons. Analysis of the resulting patterns of retrograde labeling indicates the tectofugal pathway to be comprised of at least five different channels. Cells which lie at various depths in the stratum griseum centrale (SGC) of the tectum project upon distinct subdivisions of nucleus rotundus. Anterior portions of Rt receive input from superficial most cells in the SGC, while medial and more caudal portions of Rt are projected upon by deeper SGC neurons. A ventral subdivision of Rt was found to receive its primary input from two pretectal nuclei. Additional inputs to all portions of Rt arise from nucleus reticularis superior thalami.

The various subdivisions of rotundus in turn project upon distinct portions of the ectostriatum. Thus, the segregation between the different input classes into Rt is largely retained at the telencephalic level. In contrast, the nucleus triangularis, a dorso‐medial extension of Rt which receives its input from the deepest of all SGC neurons, sends its efferents to all parts of the ectostriatum.
The effect of age on the reversibility of cellular atrophy in the LGN of the cat following monocular deprivation: A test of two hypotheses about cell growth
Authors: Cragg Brian , Anker Robyn , Wan Yoke Kum
Published: January 2005

Monocular closure soon after birth is known to reduce the growth of the deprived cells in the LGN provided that there are competing cells with normal input. When the closed eye was opened and the open eye closed after three or six weeks of monocular closure, the originally deprived cells in the LGN were able to recover their normal size. However, it was found that after 14 weeks of monocular closure there was no recovery.

The ability of the initially closed eye to excite cells in the visual cortex is known to depend on the age when eye closure is reversed in a similar manner. Thus the growth of cells in the LGN is correlated with the possession of effective synapses upon cortical cells. This result is compatible with the hypothesis that competition occurs at the cortical level. It is argued that the alternative hypothesis of competition within the LGN predicts reversibility at any age.

In some kittens, the closed eye was opened and the opposite optic nerve crushed. Some evidence was then found of structural recovery even after 14 weeks of deprivation. The hypothesis of cortical competition predicts functional recovery in such kittens, but this remains to be tested.
The localization of cholinesterase in the retina of the fetal and newborn guinea pig
Authors: Spira Arthur W.
Published: January 2005

Retinae of guinea pigs from the fortieth day of gestation to one day postnatally were processed for the localization of cholinesterases in the electron microscope according to the method of Lewis and Shute (66). Selective inhibition served to distinguish acetylcholinesterase from non‐specific cholinesterase activity. Acetylcholinesterase activity was found initially in small amounts in some regions of the outer plexiform layer at the fortieth day of gestation. At later stages it increased in distribution being observed at some photoreceptor terminals and in non‐synaptic regions of the layer. Activity was less intense initially in the inner plexiform layer but increased rapidly so that by birth it encompassed a majority of processes. Perikarya of horizontal and some amacrine and ganglion cells possessed acetylcholinesterase activity in their nuclear envelope and rough endoplasmic reticulum. The possible role of the enzyme in inhibitory circuits of the fetal retina is discussed.
The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VI. The projection onto longitudinal zones of the paramedian lobule
Authors: Brodal A. , Walberg F.
Published: January 2005

Microinjections (30–50 nl) of a horseradish peroxidase (HRP) suspension of 25% (wt./vol.) were made in different folia of the paramedian lobule of cats, and the sites of occurrence of labeled cells in the inferior olive were precisely determined. In each case only a small number of cells are labeled, aggregated in a minute area. The labeled cells are found within three only of the four olivary areas previously determined (Brodal et al., '75) to project onto the paramedian lobule (fig. 1): one area in the rostral half of the medial accessory olive, another in the dorsal accessory olive (except its caudalmost part), and a third in part of the caudal half of the dorsal lamella of the principal olive. Labeled cells were never found in the fourth area, the ventral lamella. A distinct zonal pattern in the projection is demonstrated (figs. 3, 5B): a middle longitudinal zone of the paramedian lobule receives olivary afferents from the area in the medial accessory olive, a medial zone from part of the projection area in the dorsal accessory olive, a lateral zone from part of the projection area in the dorsal lamella. This zonal projection appears to extend throughout the length of the paramedian lobule (the two caudalmost folia could not be studied). The somatotopical pattern in the projections from the accessory olives described previously (Brodal et al., '75) is confirmed. The pattern of a zonal projection obtained with the HRP‐method (fig. 5B) is simpler than that deduced by Armstrong et al. ('74) from recordings of antidromic potentials in the olive (fig. 5A). Concerning main points there is satisfactory agreement.

The phenomenon that following microinjections of HRP in superficial parts of the folia labeled cells occur within parts only of the regions of the olive which contain labeled cells following large HRP‐injections in the paramedian lobule is discussed.
The organization of the cerebellorubral projection: An experimental study in the rat
Authors: Caughell K. A. , Flumerfelt B. A.
Published: January 2005

The organization, distribution and extent of the cerebellorubral projection in the rat was investigated employing silver impregnation techniques. Cerebellar lesions of varying size were introduced stereotaxically into the deep cerebellar nuclei in a series of 32 rats and the midbrains were stained with the method of Fink and Heimer. Following large lesions which involved all of the cerebellar nuclei and their emerging fibres, numerous degenerating fibres of passage were observed to course within the brachium conjunctivam, to decaussate at the level of the inferior colliculus, and to enter the ventromedical aspect of the contralateral red nucleus. The red nucleus of the rat consists of a caudal magnocellular portion in which giant and large cells predominate and a rstral parvocellular part consisting mainly of small and medium sized cells. Within the red nucleus, coarse preterminal and terminal degeneration was distributed throughout the magnocellular portion, particularly in relation to the cell bodies and proximal dendrites. Degeneration within the parvocellular part of the nucleus was less abundant, finer in calibre and was parvocellular part of the nucleus was less abundant, finer in calibre and was scattered throughout the neuropil. Following discrete lesions of the nucleus interpositus, preterminal and terminal degeneration was restricted to the magnocellular red nucleus and it was similar in calibre and distribution to that observed in the same area following total lesions. No terminal degeneration was encountered in the parvocellular region at any time following lesions of the nucleus interpositus and only degenerating fibres of passage were seen coursing through the parvocellular region en route to thalamic levels. After lesions restricted to the nucleus lateralis, degenerating fibres were again observed coursing within the brachium conjuctivum and entering the red nucleus. In cases with nucleus lateralis lesions a pattern opposite to that observed following nucleus interpositus lesions was evident. Only passing fibres occurred within the magnocellular region and terminal degeneration was limited to the parvocellular part where it was randomly distributed, moderate in amount and fine in calibre.

This investigation has shown that the nucleus in the rat receives a major projection from the contralateral cerebellar nuclei and that a differential distribution of fibres from the nucleus interpositus and the nucleus lateralis terminates within the rubrospinal and rubroolivary portions of the red nucleus respectively.
A study of fine and coarse retino‐fugal axons terminating in the geniculate C laminae and in the medial interlaminar nucleus of the mink
Authors: Guillery R. W. , Oberdorfer M. D.
Published: January 2005

When retino‐geniculate axons of mink are labelled with 3H proline, the laminar structure of the dorsal lateral geniculate nucleus is seen to resemble that previously described in the cat. Layers A, C and C2 receive a crossed input and layers A1 and C1 receive an uncrossed input. The parvocellular layer C2 is relatively thicker in the mink than it is in the cat, and studies of retino‐geniculate fiber degeneration show that it receives fine caliber retinal afferents, whereas layers A and C receive mainly coarse afferents. The medial interlaminar nucleus receives two quite distinct crossed retino‐geniculate inputs. There is a coarse fibered component, which is continuous with lamina C, and a fine fibered component, continuous ventrolaterally with lamina C2 and extending rostro‐dorsally as a narrow streak along the margin of the nucleus lateralis posterior. The uncrossed afferents to lamina A1 are as coarse as the crossed axons to layers A and C. The uncrossed afferents to lamina C1 are somewhat finer, but are not as fine as the afferents to lamina C2. There are not many uncrossed fibers to the medial interlaminar nucleus and the distinction between coarse and fine components is not shown clearly. However, it is possible to recognize fine axons extending towards the margin of the nucleus lateralis posterior. We interpret these results as showing that there are two functionally distinct inputs to the medial interlaminar nucleus, and that the rest of the lateral geniculate nucleus may be divided into two distinct systems: A magnocellular, receiving coarse axons, and a parvocellular, receiving fine axons. The magnocellular system has one “ipsilateral” layer (A1) flanked by two “contralateral” layers (A and the dorsal part of C), while the parvocellular system similarly consists of a single “ipsilateral” layer (C1) flanked by two “contralateral” layers (C2 and the ventral part of C).