摘要:

AbstractThe central projection of the Gasserian ganglion were investigated in the pigeon,Columba livia. Lesions were placed in the ganglion either by direct surgical exposure or stereotaxically, and following survival times of one to four days, the brains stained with the Fink‐Heimer method. The main group of central axons bifurcate to from distinct ascending and descending branches, the tractus trigemini ascendens (TTA) and the tractus trigemini descendens (TTD). A smaller lateral tract also courses caudally (lTTD) separate of TTD proper to terminate in the nucleus cuneatus externus.The TTA projects topographically upon the principal sensory nucleus of the trigeminus, ending in both the pars dorsalis and a smaller pars ventralis. The neurons at the point of bifurcation of the entering radix have been designated as the pars oralis of nTTD. The TTD distributes caudally to several distinct subnuclei at each level, and extends into the cervical spinal cord. Relatively discrete regions corresponding to the pars interpolaris and caudalis were recognized.The projections to the cervical cord terminate in laminae I‐IV.There was no evidence of projections to the cerebellum, or contralateral PrV or TTD. There was a small projection to the contralateral cervical spinal cord. No clear evidence of a projection to the nucleus solitarius was found.The distribution of primary trigeminal axons is compared to that described in other vertebra

ISSN:0092-7317    

DOI:10.1002/cne.901800402

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe Golgi technique was used to study the morphology of spinal motoneurons at various stages in the early development of swimming behavior in embryos and larvae of the palmate newt,Triturus helveticus(Razoumowsky). The earliest motoneurons stained appeared to be Associated with the Mauthner‐cell system. The overall morphology of these “primary” motoneurons seems to be similar throughout the lower vertebrates and the distinctive characteristics found in earlier descriptions of those from caudate amphibia were probably due to misinterpretation. At about the time of hatching and the development of low‐frequency swimming behaviour, other motoneurons were found to innervate the axial musculature, cells with a central morphology different from those of the “primary” type. It was found likely that these “secondary” motoneurons innervate a separate muscle system concerned with tonic and “slow phasic” activity, while “fast phasic” activity in rapid swimming is supp

ISSN:0092-7317    

DOI:10.1002/cne.901800403

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe second order projections of the gustatory system in catfish were examined using both retrograde (HRP) and anterograde (degeneration and autoradiographic) hodological methods. Golgi‐stained material was used to demonstrate the different cell types in the primary gustatory sensory area, the facial lobe.Efferents from the facial lobe gather into ascending tract terminates largely in the medial funicular nucleus and the commissural nucleus of Cajal in the region of the obex. A small portion of the descending tract continues caudally to terminate in the dorsal horn of the spinal cord. The ascending secondary gustatory tract terminates mostly in the ipsilateral superior secondary gustatory nucleus in terminate in the isthmic region. A small portion of the ascending tract continues rostrally to terminate in the posterior thalamic nucleus and in the region of the nucleus lobo‐bulbaris. Sparser contralateral projections are also seen in the posterior thalamus and isthmic gustatory regions.Three cell types can be discerned in the facial lobe: small, medium and large. The small cells are intrinsic neurons, the medium cells project to the isthmic gustatory nucleus, and the large cells send fibers to the other terminal areas described above, as summarized in figure

ISSN:0092-7317    

DOI:10.1002/cne.901800404

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe end bulb of Held in the rostral ventral cochlear nucleus of the chinchilla and guinea pig was studied with the freeze‐fracture technique. The end bulb has multiple, small active zones which are uniformly distributed within the calyceal portion of this terminal. Single or small groups of active zones are surrounded by enlarged channels of extracellular space often containing processes of astrocytes. Small plasmalemmal deformations occur at these active zones. The number of these deformations is thought to be indicative of exocytotic transmitter release because they are more frequent in animals fixed in a noisy environment compared to animals fixed in a quiet environment. Thus, our study provides a basis for the quantitative study of changes in transmitter secretion at a central nervous system synapse driven by a controllable natural stimulus.The postsynaptic active zone at end bulbs resembles other excitatory synapses in the central nervous system in having an aggregate of large particles on the external membrane leaflet. Thisjunctional aggregateof particles is coextensive with the presynaptic active zone and with the postsynaptic density seen in thin sections. Severalperisynaptic aggregatesof particles are deployed around each active zone on the external membrane leaflet. These irregularly‐shaped aggregates occur preferentially opposite the channels of enlarged extracellular space and along the edge of the end bulb and are not components of intercellular junctions or plasmalemmal contacts with cytoplasmic organelles. Although the function of the different particle aggregates on the postsynaptic membrane is not clear, our findings provide a basis for studying the factors controlling and maintaining their structure as well as more evidence that a consistent relationship exists between types of synaptic action and structure of the postsynaptic membr

ISSN:0092-7317    

DOI:10.1002/cne.901800405

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe projections of visual cortical area 1 (vl) to the thalamus, pretectum and superior colliculus of the rabbit have been studied by Giolli and Guthrie (1967, 1971) using the Nauta and Fink‐Heimer methods to determine the course and distribution of degenerating nerve fibers. The present study represents a reinvestigation of these same projections utilizing the tracing method of autoradiography.An injection of3H leucine was produced within a small region of vl in each of 18 adult albino rabbits, and the brains were subsequently processed for autoradiography by the method of Cowan et al. (1972). The results have confirmed the observations of Giolli and Guthrie (1967, 71) (1) By showing that vl of the rabbit projects to the thalamic reticular nucleus, the ventral lateral geniculate nucleus, the dorsal lateral geniculate nucleus; the pulvinar, the anterior and posterior pretectal nuclei and the superior colliculus and (2) by showing that a particular retinotopic organization is present in each of these projections. However, unlike Giolli and Guthrie (1967, 1971), the present autoradiographic study has further revealed (1) that both the ventrolateral and the posterior thalamic nuclei receive inputs from vl and (2) that the nucleus of the optic tract is not innervated by axons originating from v

ISSN:0092-7317    

DOI:10.1002/cne.901800406

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe number of ganglion cells in the cat's retina, and the pattern of their distribution over the retina, have been reinvestigated. Criteria are presented for the identification of ganglion cells in Nissl‐stained whole mounts, most particularly for the distinction between small ganglion cells and neurological cells, by reference to retinas with no ganglion cells (obtained by nerve section) and to areas of retina containing a population of only small ganglion cells was counted in four retinas (mean total 116,250). The number of large or “giant” cells (presumably the somas of Y‐cells and of α‐cells ) varied from 4,200 to 7,100. Overall these cells comprised 4.0‐6.3% of the total ganglion cell population. Their distribution over the retina showed a concentration around the area centralis, with a localized minimum density at the area centralis, and a concentration in the visual streak. These concentrations of large cells were quantitatively less than the concentrations of smaller cells in the area centralis and visual streak, so that the relative frequency of large cells was minimal (mean 1.6%) at the area centralis and increased steadily up to 5.5‐6.9% in peripheral retina. Their relative frequency was distinctly lower along the visual streak that in peripheral retina above or be

ISSN:0092-7317    

DOI:10.1002/cne.901800407

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

年代:1978

数据来源: WILEY

摘要:

AbstractGanglion cell density maps of the retinas of Siamese cats show the same major features of ganglion cell distribution as are found in normally pigmented cats, in particular the area centralis and visual streak. In the retinas of the seven Siamese cats investigated, however, the area centralis was “underdeveloped” when compared with the normally pigmented cat. The beak ganglion cell density was lower and the ganglion cells usually larger than at the area centralis of the normally pigmented cat, and the characteristic blood vessel pattern around the area centralis was less developed. One animal showed a marked blood vessel abnormality, a vessel crossing the area centralis in each retina. In another animal, the distribution of ganglion cells appeared abnormal throughout the retina. Medium‐sized, possibly X‐type ganglion cells were lacking from all retinal areas, overall cell numbers were low and the distribution of ganglion cells showed a prominent visual

ISSN:0092-7317    

DOI:10.1002/cne.901800408

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

年代:1978

数据来源: WILEY

摘要:

AbstractBy sectioning one optic tract in Siamese kittens and allowing sufficient time for the affected ganglion cells to degenerate and disappear, we have obtained maps of the distribution of ipsi‐ and contralaterally projecting ganglion cells in the Siamese cat. As previous work predicted, many ganglion cells in the Siamese cat retina project contralaterally which, in the normally pigmented cat, would project ipsilaterally. The transition from the pattern of projection typical of nasal retina (all contralateral) to that typical of temporal retina (most ipsilateral) is much more gradual in the Siamese cat than in the normally pigmented cat, and is centred 1.7‐3 mm temporal to the area centralis, instead of at the area centralis. In the Siamese cat only a few ganglion cells at the area centralis project ipsilaterally, as against nearly 50% level 1.7‐30 mm into temporal retina, and overall the zone of transition may be several millimetres wide, as against about 0.2‐0.5 mm in the normally pigmented cat. Evidence is presented that the degree of the abnormality of nasotemporal division varies between individual Siamese cats and that the abnormality is more severe among large or “giant” cells than among the population

ISSN:0092-7317    

DOI:10.1002/cne.901800409

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe number of myelinated axons in the cat's optic nerve has been estimated from a partial count of sections of the nerve examined by electron microscopy. The average count obtained from four nerves was 128,600 (range 112,800‐147,200). This figure is within 10% of a previous estimate of the number of ganglion cells in the cat's retina, but is 33% lower than the only previous estimate of the number of these axons based directly on electron microscopy. Possible sources of the discrepancy are discussed.The functional implication of this total, in the context of earlier work on ganglion cell topography, are also discusse

ISSN:0092-7317    

DOI:10.1002/cne.901800410

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

年代:1978

数据来源: WILEY

摘要:

AbstractProcion yellow dye was injected intracellularly into large auditory fiber of goldfish to investigate the relationship between the response type of these fiber and their site of termination in the saccular macula.Fibers which responded to the rarefaction phases of sound were found to terminate on the hair cells located in the ventral half of the saccular macula, while those which responded to the compression phases were found to terminate on the dorsally locate hair cells. A third group of fibers, which responded to both sound phases, was found to bifurcate outside the saccular macula and terminate on both dorsally and ventrally located hair cells. Some of the fibers of this group were found to trifurcate before entering the sacular macula. Results obtained in the present study, in conjunction with the findings on the orientation of hair cells within the sensory macula, can explain the mechanism underlying the presence of three different response types of fibers in the auditory nerve of the goldfish.

ISSN:0092-7317    

DOI:10.1002/cne.901800411

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

年代:1978

数据来源: WILEY