bluuebunny/crossref_metadata_2025_split huggingface dataset:
An electron microscope study of types of receptor in the chick retina
Authors: Morris Valerie B. , Shorey C. D. 
Published: January 2005

AbstractRods, 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

AbstractUnit 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

AbstractA 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

Abstract1. 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

AbstractResponse 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

AbstractHyperstriatal 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

AbstractThe 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

AbstractHaarscheiben 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractIn 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractExpabsion 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

AbstractThe 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

AbstractThe 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.