摘要:

AbstractThe central nervous system of the leech is surrounded by fibrous tissue in which are contained muscle cells whose presumed function is to accommodate the length of the nervous system to coincide with changes in the length of the animal. In this paper a three‐dimensional reconstruction of these muscles was described. Each neuromuscular junction consists of 5–50 neural terminals closely applied to the muscle. Furthermore, some morphologic evidence for synaptic interaction between terminals was obtained. We believe that this complex morphology of the terminals indicates that there is a relatively complex integrative mechanism for neuromuscular transmission at the periph

ISSN:0092-7317    

DOI:10.1002/cne.901410102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractTo determine the arrangement of projections in the somatic sensory nuclear region in the thalamus of sheep, microelectrodes were used to locate and map neural units and groups of units responding to mechanical stimulation of peripheral receptive fields in nine animals anesthetized with Dialurethane. Most of the sensory nuclear region (70–80%) contains projections from ipsilateral oral and perioral fields, Of this volume 16–25% (10–20% of the total) was responsive to stimulation of tissues inside the mouth. The ipsilateral projections are organized differently than are the meager projections from contralateral fields. The contralateral projections are ordered in the same general pattern seen in other mammalian thalami, with caudal fields represented laterally in the nucleus, rostral fields medially, axial fields and maxillary‐nasal fields dorsally, and limbs and mandibular fields ventrally. In the ipsilateral projections, however, mandibular external fields are represented dorsally, and maxillary and nasal fields more ventrally. Still more ventral are projections from the teeth and palate, and most ventral is the representation of the tongue. In all of the ipsilateral projections, the more ipsilateral fields (fathest from the rostral midline) are represented more medially in the thalamus. The exaggerated relative volume of thalamus responding to stimulation of oral and perioral surfaces may reflect the behavioral specialization of a grazing

ISSN:0092-7317    

DOI:10.1002/cne.901410103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractThe pattern of incororation of thymidine‐H3was studied in chick embryos in which overgrowth was experimentally induced in the optic tectum. Radioautograhs were prepared for experimental and control embryos ranging in age from three to five days' incubation at post‐label periods of one hours, and eight hours. Under conditions of overgrowth, S‐phase cells are situated not only in the periphery of the wall of the tectum, but are also found scattered among mitotic cells along the ventricular border. Labeled intraventricular cells are commonly seen in the defective brains. The onset of neuroblast differentiation, as indicated by a loss in ability of certain cells to incorporate thymidine‐H3, appears to be the same in the tectum of experimental and normal embryos and takes place toward the end of the fourth day of incubation. As development continues, the pattern of labeling becomes increasingly distorted in the severely affected potions of the overgrown tectum, and neuroepithelial cells become interspersed among differentiated neur

ISSN:0092-7317    

DOI:10.1002/cne.901410104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractThe pathway of the median giant fiber in the crayfish cephalic ganglion (brain) was reconstructed from serial sections. The median giant fiber in the para‐esophageal nerve runs anteriorly and enters the brain. After turning medially, it given of a branch which further divides into two branches. These branches run ventrally and outwards and finally enter the ipsilateral antennule nerve and ventrally. It decussates and makes contact with the contralateral median giant fiber near the midline. After decussating, the fiber again divides into two branches. One runs outwards and ventrally and finally enters the contralateral antennule nerve. The other runs anteriorly at first and then turns ventrally immediately behind the rostral cellular group. Near the ventral surface of the brain the fiber turns posteriorly and connects with a large soma 100–150 μ in diameter. In its course to the soma, the main fiber decreases in width to one‐eighth of the diameter of the axon in the para‐esophage

ISSN:0092-7317    

DOI:10.1002/cne.901410105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractOrganization of the tactile receiving area of the postcentral gyrus of the spider‐monkey (Ateles) has been investigated using microelectrode recording procedures. The neocortical region in which single units or unit clusters respond to light mechanical region in skin (SmI) is smaller than the tactile receiving area as defined by earlier evoked potentials studies, failing to extend into sylvian sulcus or to the posterior margin of the postcentral gyrus. It forms a precise, detailed, and somatotopically organized pattern of representation of the complete contralateral body surface. The sensory sequence is orderly and continuous from tail to tongue with one exception, each body region in represented by a band of cortical tissue extending anteroposteriorly across SmI. The ratio, area of glabrous surface of the hand as it is for the glabrous tail pad, which correlates with the greater tactile acuity of the forme

ISSN:0092-7317    

DOI:10.1002/cne.901410106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractThe internal differentiation of the interpeduncular nuclear complex was determined by quantitative cytoarchitectonic analysis in specimens from each of the suborders of Rodentia: rat (Rattus) of the Myomorpha; guinea pig (Cavia), chinchilla (Chinchilla), and capybara (Hadrochoerus) of the Caviamorpha; and the mountain beaver (Aplodonia) from the Sciuromorpha. In each of these rodents the constituent cells of the complex ae grouped into four spatially distinct subnuclei: pars lateralis (PL), pars medialis (PM), pars dorsalis magnocellularis (PDM), and pars dorsalis parvocellularis (PDP). There is a fifth subnucleus, the paramedian, inChinchilla. Sample distributions, and means, of cell sixes were measured in each of these subdivisions in each species; and cell densities of each subdivision were determined inRrattus. In all these animals PD had the smallest cells. PDM had the largest cells, except that inHydrochoeruscells of PL, and inCaviacells of PM, were as large as those of PDM. InRattusandAplodontiaPL and PM were not different in cell size, and inRattustheir cells were of the same density. These findings cast doubt upon criteria previously used to subdivide this nuclear complex, and provide a consistent and replicable classification of its components.

ISSN:0092-7317    

DOI:10.1002/cne.901410107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractThe hypothalamo‐neurohypophyseal system of the catfish, as revealed byin situtechniques, consists of the prominent nucleus preopticus, the axonal tracts, and the neurohypophysis. The preoptic nucleus, which is composed of the pars magnocellularis and the parvocellularis, is situated on either side of the optic recess slightly anterior to the optic decussation. Axons arising from the nucleus preopticus form two ventro‐lateral tracts; bundles of axons separate out from these tracts at 10 to 12 points and extend medially to form two ventro‐medial tracts lying on either side of the optic recess. The ventro‐lateral and ventro‐medial tracts eventually merge slightly anterior tc the hypophysis to form the infundibular stalk which penetrates the pituitary and ramifies. The nucleus lateralis tuberis is situated rostral and antero‐ventral to the third ventricle and their axons join the ventro‐medial tracts.The arterial supply to the hypophysis is through a median hyophyseal vessel whose branches penetrate the pituitary along with the infundibular stalk and follow the ramifications of the neurohypophysis. A portal circulation between the hypothalamus and the hypothalamus

ISSN:0092-7317    

DOI:10.1002/cne.901410108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractBilateral electrolytic lesions were produced in eight different hypothalamic areas in weanling female rats to localize the area associated with hypothalamic obesity. Animals were maintained for five weeks and food intake measured. After sacrifice, changes in carcass fat content, plasma insulin and plasma glucose were compared to value obtained from sham‐operated controls. Only rats with lesions primarily in the ventromedial hypothalamic nuclei had significantly elevated plasma insulin levels and carcass fat content despite normoglycemia, normophagia and normal to reduced body weight gain. The results indicate the existence in the rat hypothalamus of a locus limited to the region of the ventromedial nuclei which affects insulin secretion and lipogenesis. The possible mechanisms responsible for this phenomenon are discusse

ISSN:0092-7317    

DOI:10.1002/cne.901410109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractChick embryo spinal ganglia, cultured with and without he nerve growth factor (NGF), were compared by means of electron microscopy with ganglia maintainedin vivofor an equal period of time. The results confirm an earlier report that NGF maintains and stimulates only the later‐differentiating mesiodorsal neuroblasts. However, although these cells are stimulated to grow neurites four days prematurely, cytoplasmic maturation does not accompany the outgrowth.The more‐differentiated ventrolateral neuroblasts all show some signs of degeneration after culturing with or without NGF. Those cells which appear normal in the light microscope failed to continue development like theirin vivocounterparts and are seen to have myelin figures, marked indentation of the nuclear membrane, and chromatin clumping. Crystalloid structures originally observed by Crain et al. ('64) are demonstrated to be ribosomal crystals and are found only in hyperchromatic degenerated neuroblasts.The satellite cells do not continue to developin vitro. The process of encapsulatin neuroblasts ceases in both the mesiodorsal and ventrolateral areas of the ganglia. The interrelationship of satellite cell and neuroblast develoment is discus

ISSN:0092-7317    

DOI:10.1002/cne.901410110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901410101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY