bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrograde cell degeneration in adult cat after hemidecortication
Authors: Peacock John H. , Combs C. Murphy
Published: January 2005

Eighteen adult cats were hemidecorticated by surgical aspiration and allowed to survive 14 to 54 days. Severe cell loss occurred in the following thalamic nuclei: anterior ventralis; anterior medialis, except for cell retention in the dorsomedial third; ventralis anterior; ventralis lateralis; ventralis posterolateralis; ventralis posteromedialis; lateralis dorsalis; lateralis posterior; posterior; pulvinar; geniculatum laterale, pars dorsalis; and geniculatum mediale, pars principalis. Partial cell loss was found in the anterior dorsalis, ventralis medialis, submedius, reuniens, and geniculatum mediale, pars magnocellularis. Paracentralis retained a lower than normal number of Neurons in its medial half, with scattered cells appearing throughout its lateral half and in the adjacent centralis lateralis. The pale‐staining reticular nucleus had nearly a normal complement of cells in its ventral half, whereas the dorsal half retained only scattered cells. No consistent pattern of degeneration was found in medialis dorsalis. The following structures were normal: paratenialis, interanteromedialis, rhomboidens, centralis medialis, parafascicularis, centrum medianum, and geniculatum laterale, pars ventralis. Likewise, no degeneration was displayed by subthalamic and midbrain nuclei. Throughout this study, no differences were discernible which could be ascribed to the variation in postoperative survival times.
Initial collaterals of motor axons within the spinal cord of the cat
Authors: Prestige M. C.
Published: January 2005

The histological evidence for the existence of motor initial collaterals is contradictory and insufficient. The literature is reviewed. Axons of 27 motoneurons of near term cat fetuses have been impregnated by the Golgi rapid method, and the stained structures described. A wide variety of collaterals occur randomly, mean 0.72 ± 0.12 collaterals per 100 μ. The evidence that impulses in initial collaterals of motor axons cause recurrent inhibition is discussed.
The structure of the central nervous system of the slug Arion ater L., with notes on the cytoplasmic inclusions of the neurons
Authors: Smith B. J.
Published: January 2005

The nervous system of Arion ater consists of a complex central circumesophageal nerve ring, the two buccal ganglia, the digitated ganglia in the optic tentacles ganglion masses. The supra‐esophageal ganglion mass is made up of the two cerebral ganglia, each divisible into pro‐, meso‐ and meta‐cerebrum, connected by the inter‐cerebral commissure. The pleuro‐parieto‐visceral ganglion mass consists of the three ganglion groups suggested by its name. The pedal ganglion mass consists of the ventral of the three masses and consists of the two large pedal ganglia. The distribution of the cell groups, the sizes of the cells in the different groups and the location of the interganglionic connections are described for the three ganglion masses and also for the buccal and digitated optic ganglia. A brief description of the production of paraldehyde‐fuchsin positive neurosecretion in the nerve cells and also a summary of histochemical tests carried out on the cytoplasmic inclusions of the neurons are given.
Rubro‐cerebellar connections in the cat: An experimental study with silver impregnation methods
Authors: Courville J. , Brodal A.
Published: January 2005

The rubro‐cerebellar projection has been studied in the cat with the methods of Nauta and Glees following stereotactically placed lesions in the red nucleus. A description of the intracerebellar nuclei is given in which an attempt has been made to define precisely the limits of each nucleus. The rubro‐cerebellar fibers terminate in the contralateral nucleus interpositus anterior (NIA). It cannot be decided whether the nucleus interpositus posterior (NIP) receives some fibers, but no fibers pass to the medical and lateral nuclei. A somatotopical pattern appears to be present in the projection. Rubrocerebellar fibers are thin and probably terminate in the neuropil. This fiber system is the only direct link known between the red nucleus and the cerebellum. The total number of fibers is small. Probably the fibers are collaterals from the rubrospinal tract fibers and subserve a feedback function between the red nucleus and the cerebellum.
Temporal relationship between myelinogenesis and the appearance of a basic protein in the spinal cord of the white rat
Authors: Kornguth S. E. , Anderson J. W. , Scott G.
Published: January 2005

In a previous study a low molecular weight basic protein, isolated from guinea pig brain, was shown to be localized in the myelin of adult nervous tissue. An antigenically similar protein was present in the central nervous system of a variety of mammals, the chicken and the frog. In the present study, the ability of the nervous system of the albino rat to react specifically with the fluorescent anti‐basic protein antibody was investigated during fetal and postnatal development. Although earlier stages were examined, the spinal cord of the rat was first observed to react with the antiserum in the twenty‐first day of gestation. Ultrastructural studies indicated that well formed myelin, and mature and immature synapses were present in the cervical cord at this time. A positive immune reaction was detected two days before a noticeable Weigert reaction was obtained; the sequence and spatial pattern of labeling with both techniques was similar, however. It was observed that the nucleolus and cytoplasmic web of dorsal root ganglion cells first reacted with the antiserum at a time immediately preceding the onset of rapid myelination of axonal fibers in the ganglion. The immune reaction in the cell body of the large ganglion cells diminished rapidly with the cessation of rapid myelination. The relationship of the findings to the present concept of myelinogenesis is discussed.
Relationship of cortico‐spinal tract growth to age and body weight in the rat
Authors: Bernstein Jerald J.
Published: January 2005

The capacity of neurons of the central nervous system to grow throughout an animal's life has been a subject of continuing interest. Studies were undertaken in rat to ascertain if nerve fibers of the dorsal funicular cortico‐spinal tract increase in diameter and/or number during the animal's growth.

Animals were divided into four experimental groups: (a) 4‐weeks, 156 gm; (b) 10‐weeks, 181 gm; (c) 10‐weeks, 281 gm; (d) 9–months, 563 gm. Spinal cords were fixed by perfusion with 2.5% glutaraldehyde and the eighth thoracic segment immersed in 1% osmic acid. Counts and size measurements were made from photomicrographs of 2 μ sections.

The average number of myelinated nerve fibers in the tract was 13,723. There were no statistical differences in number of fibers between the various age and weight groups. Growth in this tract was related to increased fiber diameter with age concomitant with increased area of tract and of spinal cord. As the diameter of individual nerve fibers increased, myelin sheath and axis cylinder diameters increased proportionately.

The cortico‐spinal tract of the rat grows by increase in nerve fiber diameter from 4‐weeks to at least 9‐months of age. It is suggested that by means of this mechanism of central nervous system growth, the nerve fiber can transmit information at a more rapid rate over greater distances as growth proceeds, thus allowing for sensory and motor coordination of the animal during changes in body size.
The nucleus ambiguus of the rabbit
Authors: Lawn A. M.
Published: January 2005

Each nucleus ambiguus of the rabbit contains about 1,500 cells and is approximately 4 to 5 mm long. The author confirms the previously described division of the nucleus into a rostral compact formation, 1.6 mm long, and a caudal diffuse formation occupying the remainder of the nucleus. He further subdivides the compact formation into a lateral part, the principal column, and a medial part, the medial column. These divisions and the cytological differences between the cells in different divisions are illustrated. The cells in the medial column are more similar in appearance to those of the diffuse formation, with which they probably form a continuous column, than to those of the principal column, which are smaller, and have less distinct Nissl granules.
Distal retraction balls in the neurohypophysis after transection of the pituitary stalk
Authors: Daniel Peter Maxwell , Prichard Marjorie Mabel Lucy
Published: January 2005

During the first few weeks after transaction of the pituitary stalk retraction balls (Cajal) were found on the fibers of the hypothalamo‐neurohypophyseal nerve tract not only above but also in large numbers below the level at which the nerve tract had been cut. The latter, termed distal retraction balls, are clearly seen in routinely stained sections but are even more conspicuous after impregnation with silver. Distal retraction balls were found in the isolated neurohypophysis of man, monkey, goat and sheep. It is suggested that the development of so many retraction balls distal to the site at which the nerve tract had been severed was due largely to conditions resulting from the peculiar anatomical arrangements of the pituitary gland. Stalk section causes infarction and consequent swelling of pars distalis; this swelling, occurring in the confined space of the pituitary fossa, compresses the neurohypophysis, thereby squeezing out axoplasm from the cut ends of the isolated nerve fibers to form the distal retraction balls. Distal retraction balls were not identified with certainty in the rat, possibly because in this species the pituitary gland is not enclosed in a bony fossa, and the neurohypophysis is therefore not compressed when pars distalis swells.
Organization of the spino‐cervico‐thalamic system
Authors: Ha Hongchien , Liu Chan‐Nao
Published: January 2005

In addition to the classical spino‐thalamic and medial lemniscal systems in mammals, there is a spino‐cervico‐thalamic system relayed by the nucleus cervicalis lateralis. This nucleus is a well defined nucleus situated in the lateral funiculus, ventrolateral to the dorsal horn. It is a slender cell column, extending from the lower portion of the medulla through the upper two cervical segments of the spinal cord of the cat as well as some other mammals including primates.

Experimental studies have shown that the nucleus cervicalis lateralis serves as a second relay nucleus, projecting to the ventral posterior lateral nucleus of contralateral thalamus. It receives impulses from dorsal root fibers via three different first relay nuclei, namely, Clarke's column, ventral spinocerebellar tract neurons, and the large‐sized neurons in dorsal horn of lower lumbar through sacral segments.

The morphology of neurons of the nucleus cervicalis lateralis is unique. The dendrites are well confined in the nucleus and most of them run in the longitudinal direction. Golgi studies revealed the collaterals from dorsal portion of the lateral funiculus to the nucleus. Three types of terminals, namely, bouton of passage, terminal clusters and basket‐like terminals, were found in this nucleus.
The neurohistology of quiescent mammary tissue in Lepus albus
Authors: Ballantyne Bryan , Bunch G. A.
Published: January 2005

The neurohistology of quiescent mammary tissue from adult female albino rabbits was investigated by cholinesterase histochemistry.

Dense plexuses of nerve fibers enter the nipple in the dermis surrounding the lactiferous ducts, and unite at the summit of the nipple to form an apical plexus. From the plexuses at the base of the nipple nerves pass between deep epidermal invaginations, to form a basal nipple sub‐epidermal plexus, A sub‐epidermal plexus of fibers of small diameter arises from the apical dermal plexus. At the base of the nipple extensive nerve plexuses occur around smooth muscle. The only endings are intraepidermal nerve terminals from the apical sub‐epidermal plexus. In mammary skin outside the nipple area the dermal and sub‐epidermal plexuses are more attenuated. Longitudinally or circularly arranged nerves occur around hair follicles. Peri‐arterial plexuses are present throughout the mammary tissue. The myo‐epithelial cells and alveoli are not innervated.

The neurohistological pattern suggests a spatio‐temporal sensory innervation concerned in neurohormonal reflexes of milk secretion and ejection, and neural reflexes of nipple erection. Autonomic motor innervation regulates blood flow and promotes nipple erection. The absence of myo‐epithelial cell and alveolar innervation indicates a solely endocrine effector regulation of milk ejection and secretion.
Neuroglial relationships in the thoracic ganglion of the fiddler crab, Uca
Authors: Malzone W. F. , Collins G. H. , Cowden R. R.
Published: January 2005

A cytological and ultras Uitasructural investigation was undertaken on the thoracic ganglion of the fiddler crab Uca sp., in an attempt to find morphological evidence for functional relationships between neurons and extraneuronal cells.

Neurons of several sizes and four types of extraneuronal cells were present in this tissue. These included capsular cells intimately associated with neurons and “endothelial cells” closely associated with a complex branching vascular system. The vascular system ramifies with vessels which decrease in diameter, terminating in extravasculax spaces in intimate contact with the capsular cells. The findings suggest that extraneuronal cells mediate between the vascular system and the metabolically active neurons via modifications which include: (1) A complex branching vascular system, (2) perivascular processes containing numerous clumped mitochondria and complex arrangements of 200 Å spaces between cytoplasmic islands; (3) a parallel array of canalicular elements within capsular cell processes; (4) multicomponent bodies found in several locations including the cytoplasm of extraneuronal cells and the neuronal cytoplasm. These findings support the hypothesis that extraneuronal cells transport macromolecular materials and are thus involved in meeting the metabolic requirements of neurons.
Electrophysiological characteristics of tectal and thalamo‐cortical divisions of the visual system in lower vertebrates
Authors: Karamian A. I. , Vesselkin N. P. , Belekhova M. G. , Zagorulko T. M.
Published: January 2005

Electrophysiological characteristics of the visual system have been investigated on an ascending phylogenetic scale in submammalian vertebrates. In cyclostomes and plagiostomes the only system of vision is retino‐tectal. In lampreys spread of excitation from visual centers to descending paths of the spinal cord occurs readily, as a manifestation of diffuse, primitive brain. As a result of progressive cephalization, a new retino‐thalamo‐cortical system arises in amphibia and reptilia. The retino‐tectal system, however, retains its leading role. Optic tectum visual potentials are of short latency, displaying stability of pattern and aptitude to reproduce stimulation rhythm, making them comparable to primary responses of the mammalian cortex. The phylogenetically more recent retino‐thalamocortical system has not attained structural or functional maturity. Due to its diffuse organization, visual potentials generated in the surface cortical layer are of long latency, displaying aptitude to fatigue and recruiting on rhythmical stimulation, sensitivity to nembutal; being unlike the primary responses of the mammalian cortex, they should rather be regarded as responses of a non‐specific type. Electrical stimulation of dorsal thalamic structures in the frog, turtle and varanus also fails to evoke cortical responses of a primary type. In the course of phylogenetic development, the retino‐thalamo‐cortical system evidently goes through a stage (amphibia, reptiles), when representation of the function of vision is of a mainly non‐specific nature.
The number of nerve cells in the cerebral cortex of man
Authors: Pakkenberg Henning
Published: January 2005

In a normal brain fixed by perfusion, the number of nerve cells in the cortex was determined by counting the nucleoli in sections of measured thickness. The Abercrombie correction formula was used, and a mean value obtained of 17,560 cells per mm3. The linear shrinkage was determined in three other brains, both after fixation in alcohol‐formalin and after paraffin embedding and sectioning. A 20% shrinkage in volume was found after fixation, and a 74% shrinkage in volume after the histological procedures. Reckoning with a cortex volume of 570 ml in the unfixed brain, the total number of nerve cells in the cortex examined is found to be 2.6 × 109 cells.
Cell frequencies in the human inferior olivary nuclear complex
Authors: Moatamed Farhad
Published: January 2005

Cerebellar afferents from the inferior olivary nuclei arise from about one million nerve cells. This figure was determined by counts and estimates carried out on four complete series of human brain‐stem sections of a new‐born, a three‐month‐old infant, a 42‐year‐old male and a 56‐year‐old male. Cell frequencies in all four cases were nearly identical. About 7% of this total belongs to the two accessory nuclei, believed to project to the archeocerebellar cortex.

Cell sizes differ between the main and the two accessory olivary nuclei, the former having a mean cell size of about 400 μ2, the latter about half this size. Comparing infant and adult cell size, there is a threefold increase in volume from infancy to adulthood. Packing density of nerve cells in the infants is about twice that of the adults. The ratio of nerve cells to glia cells is 1:4 in the adults and 1:6.7 in the infants.
Magnocellular neurosecretory centers in the rat hypothalamus
Authors: Price Peterson R.
Published: January 2005

Hypothalami from normal rats were examined after preparation with Gomori's chromalum‐hematoxylin stain for neurosecretory material. In addition to the supraoptic and paraventricular nucleii, five additional nuclear masses of neurosecretory cells were found. These all formed more or less compact cellular groups, clearly demarcated from surrounding neural tissue and with constant location from animal to animal. One nucleus, immediately posterior to the anterior commissure, along the ventricular wall, is termed anterior commissural. Two others, being dorso‐lateral to the columns of the fornix, are termed anterior and posterior fornical. Midway between the paraventricular nucleus and the optic tract, a characteristically shaped nucleus of very compact cells, the nucleus circularis, is encountered. Finally, another group of cells is seen dorsal to the optic tract in the middle of the medial forebrain bundle, the nucleus of the medial forebrain bundle.
The neuronal components of the optic nerve of the crayfish as studied by single unit analysis
Authors: Wiersma C. A. G. , Yamaguchi T.
Published: January 2005

Unit responses were obtained from the optic nerve of the crayfish, Procambarus clarki (Girard) with steel needles. Eighty‐three repeatedly recognized elements are described. They range from bundles of primary sensory fiber to complexly reacting multimodal interneurons. Visually reacting fibers fall into two main classes, one class reacts tonically to overall illumination, the other responds to moving objects. Sustaining fibers react to increased light with increased output, dimming fibers are active in the dark and inhibited by light. Fourteen sustaining and four dimming fibers are described. The main movement fiber type, of which eleven have been found, responds to shadows. They “habituate” quickly and react best to movement of small black objects. All these fibers, and some others, are present as centrifugal elements from the other eye. All these fibers, and some others, are present as centrifugal elements from the other eye. Four fibers, two sustaining and two movement ones, change their fields with positions of the animal. These “space‐constant” fibers “look” at the sky from all positions for which possible and are otherwise “blind.” Mechanoreceptive interneurons form a bundle between the first and second classes of optical fibers. Seventeen members are described. Five multimodal fibers, with combined visual and mechanoreceptor input are described. Maps of the approximate locations of the units in the cross‐section of the optic nerve are presented. The number of times specific fibers were found exceeded 50 for 28.
The distribution of the internal carotid circulation in the brain of the macaque monkey (Macaca mulatta)
Authors: Coceani F. , Gloor P.
Published: January 2005

The distribution of the internal carotid circulation of the macaque brain was studied by using a method of intracarotid dye injections which produced no appreciable disturbance of the dynamics of the cerebral circulation. The areas in cortical and diencephalic structures supplied by the carotid circulation are described and displayed semidiagrammatically in a set of figures. The carotid artery supplies most of the lateral and mesial surfaces of the cerebral hemisphere, whereas the hemispherical portion supplied by the posterior cerebral artery is confined to the occipital and inferior temporal region. Left and right internal carotid territories overlap widely across the midline in cortical areas due to the existence of a single pericallosal arterial trunk formed by the junction of both anterior cerebral arteries. In the diencephalon the segregation of the territories of the left and right internal carotid arteries is sharp, except in its anterior‐most portion. The pattern of internal carotid supply to the thalamus is somewhat variable, the most lateral structures are most consistently supplied by this vessel, whereas the more medial structures, even those lying far rostral within the thalamus, are supplied by the posterior cerebral artery. The territories of the two vessels overlap considerably within the thalamus. In a certain number of animals, the posterior cerebral artery is part of the internal carotid, rather than of the vertebral‐basilar system.
The cytoarchitecture of the brain stem of the domestic pig
Authors: Breazile James E.
Published: January 2005

The cytoarchitecture and topography of some brain stem nuclei of the pig have been studied intransversely and sagitally cut, Nissl and Weigert stained, semiserial section. The cytology of those brain stem nuclei which receive an afferent supply from the ventrolateral funculus of the spinal cord is described. This study was found to be a necessary prologue to the study of distribution and terminations of spinal cord afferents to the brain stem in this species.

The recognition of a nuclear pattern within the brain stem of the pig which is quite similar to that described in other species is noted.
An electron microscope study of types of receptor in the chick retina
Authors: Morris Valerie B. , Shorey C. D.
Published: January 2005

Rods, double cones which comprise a principal and an accessory cone, and two types of single cones occur in the chick retina. The rod is narrow and contains a paraboloid, a basal nucleus and a small synaptic body with long synaptic lamellae. The principal cone has a pale‐staining oil droplet and is aligned against an accessory cone, which has a paraboloid, no oil droplet, but a small granular vesicle instead. The synaptic body of the principal cone is large and partly surrounds that of its associated accessory cone. The synaptic body of the accessory cone has a long process extending into the outer plexiform layer. Single cone type I has a dark oil droplet and the mitochondria in the ellipsoid are dense with cristae. Single cone type II has a lighter‐staining oil droplet and fewer cristae. The synaptic bodies of both types of single cone lie vitreal to those of rods and double cones. Fibres connect the synaptic body to the nuclear region in single cones and accessory cones, but not in rods and principal cones. Another type of synaptic body, which is not that of a receptor, occurs in the outer plexiform layer. Groups of small vesicles, like those in the synaptic body, occur near the base of the inner segments; synaptic vesicles may originate here. Muller cells separate each receptor, except the members of a double cone, at the outer limiting membrane and may position the receptors in relation to the pigment epithelium to allow a radial orientation of the inner and outer segments.
Unit analysis of the pretectal nuclear group in the rat
Authors: Siminoff Robert , Schwassmann Horst O. , Kruger Lawrence
Published: January 2005

Unit responses to visual stimuli in the pretectal region of the rat were investigated with steel microelectrodes. Most units could be classified into two broad categories; “phasic” (brief on and off discharges) and “tonic‐on” (sustained discharge during the visual stimulus). The responsive region appears to be coextensive with the n. praetectalis anterior (Pta) which can be divided into a dorsal portion containing “phasic” units and a ventral portion containing “tonic‐on” units. The projection of the contralateral visual field is a mirror reversal of the field projection onto the superior colliculus. “Tonic‐on” units may suserve total luminous flux detection necessary for the pupillary reflex. The topographical organization of units within Pta, as well as their diverse properties may account for residual visual function in animals with extensive lesions of the main visual pathways.
Bilateral relationships of the trigeminal mesencephalic nuclei and mastication
Authors: Smith R. Dale , Marcarian Heront Q. , Niemer William T.
Published: January 2005

A surgical procedure was developed in monkeys and cats to permit investigation of the central projections of the proprioceptors from the isolated medial or lateral pterygoid muscles, as well as from the intact masticatory muscle joint complex of the same animal. Evoked potentials were recorded simultaneously from the right and left mesencephalic nuclei of animals mounted in a Horsley‐Clark apparatus. All electrode placements were verified histologically. Depression of the mandible on the intact side of the head evoked potentials in the ipsi‐ and contralateral mesencephalic nuclei, as did tension applied to the isolated medial or lateral pterygoid muscle. It is believed that these potentials are representative of impulses projected via a polysynaptic chain from the nuclear chain type of neuromuscular spindles, Golgi tendon organs and joint receptors, each of which projects bilaterally and contributes to the correlation and integration of the function of the muscles of mastication.
The subcortical distribution of optic fibers in Saimiri sciureus (Squirrel monkey)
Authors: Campos‐Ortega J. A. , Glees P.
Published: January 2005

1. The optic subcortical connections in a new world monkey (Saimiri sciureus) have been examined with the Nauta and Glass silver impregnation.

2. Terminal degeneration following optic nerve sectioning reveals a laminated dorsal cell mass, which contains separate points of termination for crossed and uncrossed optic fibers.

3. Experimentally it can be shown that the two magno‐cellular laminae have separaate connections. The most ventral lamina (lamina 1) receives contralatieral fibers, lamina 2 ipsilateral fibers. The dorsal cell mass in the normal material undivided shows experimentally the following lamination: layers 4 and 6 receive contralateral fibers while layers 3 and 5 receive ipsilateral fibers.

4. Further points of termination for optic impulses are: the nucleus pregeniculatus, the nucleus limitans, and the superior colliculi (stratum poticum).

5. Fibers of the accessory optic system are crossed entirely and terminate in the nucleus of the accessory optic tract.
The hyperstriatal region of the avian forebrain: Somatic and autonomic responses to electrical stimulation
Authors: Cohen David H. , Pitts Lawrence H.
Published: January 2005

Response to constant‐current stimulation of the corticoid region and hyperstriatum were studied in 15 chronically implanted pigeons. The principal somatic response in the semi‐restrained bird was head movement, which was accompanied by appropriate body and limb response in the unrestrained animal. A correlation between electrode location and response suggested a topographical organization of the corticoid region and accessory hyperstriatum with respect to direction of head movement. A number of variables affected the responses, including initial head position, stimulation parameters and anesthesia.

Stimulation also produced moderate tachycardia and less often cardiac arrhythmia. Respiratory rate and amplitude changes were also evoked. A diffuse cardiac and respiratory representation was suggested by a lack of correlation between these response and electrode location.

A possible pathway mediating these response is considered, and possible relationships between the corticoid region, accessory hyperstriatum and ventral hyperstriatum are discussed.
Connections of efferent fibers from hyperstriatal areas in chicken, raven, and African lovebird
Authors: Adamo Norma Jean
Published: January 2005

Hyperstriatal lesions were produced by suction in chickens, ravens and African lovebirds. Efferent connections from the ablated regions were determined by examining serial sections stained by the Nauta‐Gygax method. All three species utilize the septo‐mesencephalic tract to reach other brain regions, but in two ravens degeneration is also observed in the lateral forebrain bundle. The nucleus superficialis parvocellularis, nucleus lateralis anterior, nucleus intercalatus, pretectal nucleus and optic tectum are sites of termination common to all three species. Terminations in other structures are found depending on the species examined and/or the rostro‐caudal position of the lesion. The nucleus dorsolateralis anterior, lateral geniculate nucleus, nucleus tractus tecto‐thalamici cruciati, nucleus hypothalamicus posterior, and medial and lateral pontine nuclei are areas which show degeneration in specific birds.
The course and termination of the striae of Monakow and held in the cat
Authors: Fernandez Cesar , Karapas Francis
Published: January 2005

The course and termination of the stria of Monakow and stria of Held were studied with Nauta‐Gygax technique following a localized lesion of the dorsal cochlear nucleus in the cat. A dense preterminal degeneration within all homolateral primary cochlear nuclei and a tract of degenerated fibers crossing the restiform body dorsally were found. This tract divides in two branches forming the stria of Held and stria of Monakow.

The stria of Held followed the course described by classical anatomists. In the homolateral side, the stria gave terminals to the medial and lateral preolivary nuclei, lateral superior olive nucleus and retro‐olivary groups. In the contralateral side, preterminal degeneration was found in the medial preolivary nucleus and medial retro‐olivary group.

The stria of Monakow is essentially crossed pathway given numerous terminals to the contralateral dorsal retro‐olivary group, rostral part of the lateral preolivary nucleus, the ventral and dorsal nuclei of the lateral lemniscus, and nucleus of the inferior colliculus.
The structure and function of the Haarscheibe
Authors: Smith Kenneth R.
Published: January 2005

Haarscheiben have been studied in several species, using light and electron microscopy as well as electrophysiological techniques. These specialized plates of epidermis contain many Merkel Cell‐neurite complexes arranged just above the basement membrane and beneath a row of colmnar cells. The adequate stimulus for evoking responses in the sensory nerve fibers serving Haarscheiben is pressure upon the tylotrich (hair) which, in turn, compresses the Haarscheibe, a highly sensitive, slowly adapting, modality‐specific touch receptor. The pattern of distribution and innervation of Haarscheiben in rats has been mapped. The ultrastructure of the Merkel cell‐neurite complex reveals that myelinated neurites lose their myelin within a few microns of the epidermis and penetrate the basement membrane, to end as disciform terminals upon the bases of Merkel cells. Merkel cells probably serve an important function in transducing mechanical force into neural action potentials, and their cytoplasmic granules may play a role in this function.
Development of the corpus callosum and cavum septi in man
Authors: Rakic Pasko , Yakovlev Paul I.
Published: January 2005

The development of the cerebral commissures, septal area, primordium hippocampi, septum pellucidum and cavum septi was followed from early embryonal stages to term. The growth of the corpus callosum was measured from the fourth fetal month to maturity. It was concluded that the development of the corpus callosum is preceded by the infolding of the dorsal part of the lamina reuniens of His (1904) in the region of the prospective hippocampus into a median groove, and by fusion of its banks into a massa commissuralis which becomes the bed for corpus callosum, as was described by Zuckerkandl (1901) in mice. The cavum septi arises as a pocket between the walls of the infolded primordium hippocampi and bridged by the corpus callosum. The pocket is open at first into the interhemispheric fissure and remains open in the adult rodents, carnivora and monkeys (Rhesus). The pocket is sealed by the rostrum of corpus callosum in cetacea (Tursiops), apes and in man. Interstitial cavitation in the commissural plate as postulated by Hochstetter (1929) has not been observed.
Hematic and fluid barriers of the retina and vitreous body
Authors: Rodriguez‐Peralta Lorenzo A.
Published: January 2005

A method employing non‐toxic doses of diaminoacridines combined with ultrafreezing and drying techniques, fluorescent microscopy, and fluorometry has been used in this study of hematic and fluid barriers in the vitreal chamber and surrounding tissues.

These studies have demonstrated: that diaminoacridine concentrations of 3.38 × 10−6 M in the circulating blood failed to penetrate into the retina, vitreous body, and optic nerve head; that there are hematic barriers preventing the penetration of diaminoacridines into these tissues and fluids; that the barriers are located in the pigment epithelium, inner layer of ciliary epithelium, iridial retina, and vascular endothelium of retinal and optic nerve vessels; and that the precise anatomical sites of these barriers are given by (a) the part of the cell membrane of ciliary epithelium and iridial retina facing the posterior eye chamber, (b) the part of the cell membrane of pigment epithelium facing the retina, and (c) the part of the endothelial cell membrane of retinal and optic nerve head vessels facing the vascular lumen.

Injections in the vitreal or aqueous chambers to produce 3.38 × 10−6 M diaminoacridine concentrations inside either chamber have demonstrated that the hematic barriers which prevent the penetration of diaminoacridines from the blood into the retina and vitreous permit their passage in the opposite direction. The diaminoacridine solutions follow special patterns in their elimination from the vitreous of different species according to the type of retinal vascularization.
Comparison of the localization of acetylcholinesterase and non‐specific cholinesterase activities in mammalian and avian retians
Authors: Nichols Charles W. , Koelle George B.
Published: January 2005

The localization of acetylcholinesterase and non‐specific cholinesterase was studied in the cone retinas of the pigeon and ground squirrel, and in the predominantly rod retinas of the rabbit, rat and cat. The enzymes were localized histochemically using the copper or gold thiocholine method. In the cone retinas, acetylcholinesterase was found in discrete bands in the inner plexiform layer. Cells corresponding in position and morphological detail to amacrine cells were stained for acetylcholinesterase. Cells of the ganglion cell layer that resembled displaced amacrine cells were also stained for acetylcholinesterase, as well as other cells that appeared to be ganglion cells. No stained processes could be followed from these latter cells, however. The horizontal cells were stained for non‐specific cholinesterase; these cells were localized to specific areas of the retina, which differed in the two species. In the predominantly rod retinas, there was no staining for non‐specific cholinesterase, but there was diffuse staining for acetylcholinesterase throughout the inner plexiform layer. In the rabbit, this staining pattern was not changed by chronic section of the optic nerve. No stained amacrine cells could be seen distinctly in any of the three species with predominantly rod retinas. After an intravenous dose of diisopropyl phosophorofluoridate sufficient to inactivate all the retinal acetylcholinesterase, however, synthesis of new enzyme could be followed in the amacrine cells and their processes. In all five species examined, therefore, the amacrine cells appeared to be the major or sole source of acetylcholinesterase for the inner plexiform layer of the retina. The possible function of this enzyme with regard to synaptic transmission in the retina is discussed.
Trigemino‐cerebellar fiber connections in the goat studied by means of the retrograde cell degeneration method
Authors: Karamanlidis A.
Published: January 2005

In this study lesions were placed in the cerebellum of young goats and the trigemino‐cerebellar connections investigated by means of the method of retrograde cell degeneration. The preparations were stained according to the Klüver‐Barrera and the thionin methods. It was found that fibers arising from the spinal Vth nucleus (its nuclei oralis and interpolaris) enter the cerebellum via the homolateral restiform body and seem to terminate in the anterior vermis. Additionally, the existence of distinct ventral cellular group in both the chief sensory and the spinal Vth nuclei was pointed out. This group was found to project also to the cerebellum (very possibly the flocculus), as degeneration was absent from this group in experiments with the floculus completely intact. The chief Vth nucleus proper was found in these experiments to be intact except for a few degenerated cells lying dorsal to the ventral group. Finally, the mesencephalic root nucleus exhibits also retrograde cell degeneration but only in cases where the brachium conjunctivum (homolaterally) has been partly lesioned.
The microcirculation of the area postrema in the rat
Authors: Roth Gerald I. , Yamamoto William S.
Published: January 2005

The validity of current theories concerning the function of the area postrema ultimately rests on the nature of its microcirculation. Therefore a detailed study of the vasculature of the postremal region was undertaken in the rat.

The findings indicate a singular arteriolar supply from branches of the posterior inferior cerebellar arteries. These vessels are caudal, intracranial branches of the vertebral arteries. Networks of enlarged capillaries are prominent features of sections taken through the area postrema. These enlarged capillary channels are re‐entrant. At the borders of the structure they are joined by short interconnecting vessels to capillaries of smaller caliber typical of the medullary tissue. The bed is considered to be a portal system because two distinctive, serially connected capillary beds are interposed between artery and vein. No arteriovenous shunts or thoroughfare channels are observed in the rat, contrary to reports of this type of vessel in other species.

This microcirculatory pattern would seem to be adequate to current theories of postremal function, which attribute neurosecretory or chemosensory functions to this region.
Nuclei of the diencephalon of Hylobatidae
Authors: Kanagasuntheram R. , Wong W. C.
Published: January 2005

The nuclear organization of the diencephalon of the gibbon is described and a comparison is made with that of prosimian primates, macaque and chimpanzee. The nuclear configuration is generally similar in Hylobates and Symphalangus except that in the latter genus the lateral geniculate body becomes six layered in the caudal third of the nucleus while the four laminar pattern prevails throughout the entire nucleus in Hylobates. The thalamus of gibbon shows an advance over that of the macaque in the enlargement of the nucleus medialis dorsalis, the centrum medianum and the pulvinar. The nucleus ventralis intermedius, composed of large cells assumes remarkable proportions in the gibbon while the nucleus ventralis posterior shows a corresponding reduction. In the hypothalamus the nucleus hypothalamicus ventromedialis and the nucleus mammillaris medialis are very large but the nucleus hypothalamicus dorsomedialis shows a marked reduction in size.
The early brain development of the dog
Authors: Houston Marshall L.
Published: January 2005

The neural plate in dog embryos forms cranial to the primitive streak by 15 days and elongates as the primitive streak regresses. The neural folds contact each other at the third rhombomere at the seven somite stage. Neural crest cells are present in the early somite embryos from the optic primordia throughout the brain. Differentiation of these cells results in the anlagen of cranial nerve ganglia. Regional differentiations of the neural plate establish the prosencephalon as a broad cranial segment by four somites, with a closed neural tube, optic vesicles and infundibulum by 15 somites. The mesencephalon is an almost spherical vesicle and the rhombencephalon has become subdivided by 15 somites into seven neuromeres. The cranial flexure begins in the mesencephalon at ten somites, and the cervical flexure at the fourth somite level by 20 somites. The pontine flexure first appears at 32 somites. Secondary divisions of prosencephalon and rhombencephalon from a typical five vesicle brain anlage. The telencephalon is present at 20 somites as a bulge from the roof of the diencephalon. Telencephalic vesicles appear by 30 somites. The mesencephalon elongates slowly but is not divided into neuromeres. The rhombencephalon by 25 days has differentiated into the primordia of the cerebellum and pons cranially (the metencephalon) and the medulla oblongata caudally (the myelencephalon).
Evolution of somatic sensory specialization in otter brains
Authors: Radinsky Leonard B.
Published: January 2005

Expabsion of the coronal gyrus in Lutra and Pteroneura indicates a somatic sensory specialization of the head region, presumably in the form of extremely sensitive vibrissae. Enlargement of the primary somatic sensory projection area of the forelimb in Amblonyx, Aonyx, Parainyx and, in a different way, in Enhydra, correlates with anatomical and behavioral observations indicating increased tactile sensitivity of the hand of those otters. Fossil endocranial casts reveal that such specializations, at least in the Lutra and Aonyx groupe, were developed as far back as about ten million years ago. Potamotheirium, representing an independent line of aquatic mustelids, had an enlarged coronal gyrus 25 million years ago, at a time when in other respects it; brain was still quite primitive; descendants of Potamotherium survived until ten million years ago in North America.
Rubrobulbar projections in the rabbit. A light and electron microscopic study
Authors: Mizuno Noboru , Mochizuki Kaori , Akimoto Chihiro , Matsushima Ryotaro , Nakamura Yasuhisa
Published: January 2005

The crossed rubrobulbar fibers coursing in association with the classical rubrospinal tract in the rabbit were investigated by means of the Nauta and the Fink‐Heimer methods. The synaptic organization within the terminal areas of the rubrobulbar fibers were also studied electron microscopically.

The crossed rubrobulbar fibers are distributed to the ventral portion of the reticular area intercalated between the motor and the main sensory nuclei of the trigeminal nerve, to the ventrolateral part of the lateral parvocellular reticular formation, the dorsal region of the facial nucleus, the subtrigeminal portion of the lateral reticular nucleus, and the rostrolateral part of the main portion of the lateral reticular nucleus. Small to medium‐sized, electron‐dense, degenerated synaptic knobs were observed in the dorsal region of the facial nucleus and in the rostrodorsolateral part of the lateral reticular nucleus. All of the synaptic vesicles contained in the degenerated synaptic bags were spherical. Almost all of the degenerated synaptic terminals were in contact with dendritic profiles. Sporadic electron‐dense synaptic knobs contacting the soma of nerve cells were encountered only in the dorsal aspect of the facial nucleus.
The development of the mesencephalic nucleus of the trigeminal nerve in the chick
Authors: Rogers Lynn A. , Cowan W. Maxwell
Published: January 2005

The normal development of the mesencephalic nucleus of the trigeminal nerve has been studied in a series of chicks from the fourth day of incubation until the eighteenth day post‐hatching. In addition, the time of origin of the cells in the nucleus has been determined by 3H‐thymidine autoradiography, using a variant of the cumulative labeling method.

The fully‐formed nucleus consists of two distinct groups of unipolar cells, a numerically larger medial division within the tectal commissure and a smaller, lateral division within the stratum griseum periventriculare of the optic tectum. The cells in the lateral group are, on the average, larger than those in the medial part of the nucleus at all stages of development. The entire population of neurons is generated between the third and fourth days of incubation (stages 14 to 24) with the cells in the lateral division being formed slightly earlier (stages 14 to 20) than the medially located cells (stages 16 to 24). When the nucleus is numerically complete, at the eighth or ninth day of incubation, it contains between 4,000 and 4,500 cells. Between days 11 and 13 there is a dramatic loss of cells, especially from the caudal part of the nucleus, to a final population of about 1,100 neurons. This normally occurring cell loss seems to occur at the time muscle spindles are being formed, and appears to be due to the inability of the outgrowing processes of the cells to form appropriate peripheral contacts since it is accentuated by the early extirpation of the mesoderm of the mandibular lobe. These experiments also suggest that in the chick the jaw musculature is, in part, innervated bilaterally by the mesencephalic nucleus.
An ultrastructural analysis of the photoreceptors of the squid and their synaptic connections. II. Intraretinal synapses and plexus
Authors: Cohen Adolph I.
Published: January 2005

The plexus level of the retina of the common squid, Loligo pealei was studied by electron microscopy and was found to be layered in the sclerad direction by imprecise zones respectively characterized by receptor collaterals, synaptic profiles, horizontal fibers, and receptor axons and other neurites ensheathed in glia. Receptor axons characteristically contained microtubules and dense mitochondria, passed vertically through the layer of horizontal fibers and then turned horizontally as they became collectively ensheathed. Receptor collaterals emerged at the level of the most proximal receptor nuclei and at intermittent regions across the retina entered into gap junctions with similar appearing processes. Horizontal fibers may represent efferents which originate in similar fibers sheathed in retinal glia and also seen in the optic nerve and lobe. They occasionally formed en passant synapses on receptors which were characterized by clusters of small clear vesicles and increased membrane density. They also gave rise to branches whose terminals have not been directly traced. Some of these branches showed both clear and dense‐cored vesicles. Synapses on receptors had a cluster of small clear vesicles and one to three large dense‐cored vesicles which were not involved in the cluster. Increased density of the synaptic membrane was best seen after primary osmium fixation. Aldehydeosmium and direct osmium fixed material are presented for comparison. Fibers somewhat similar in appearance to horizontal fibers but which were smaller and more dense had regions filled with smaller dense‐cored vesicles which never showed clustering on a membrane or a consistent relationship with a putative post‐synaptic cell. The possible origins of the neurites of the retinal plexus are discussed.