摘要:

AbstractA detailed description is given of the distribution of zinc in three areas of the domestic pig hippocampal region, viz., the entorhinal area, the parasubiculum, and the presubiculum. Zinc was demonstrated histochemically with use of the Neo‐Timm method, a recent modification of the sulphide silver procedure. Each of the studied areas showed a distinctly stratified staining pattern, which has been correlated in detail to fields and layers defined on the basis of cyto‐ and fibroarchitecture, providing a combined chemo‐ and cytoarchitectonic map. The staining was primarily confined to the neuropil, although stained nerve cell bodies were encountered in all three parts of the hippocampal region.Two main subfields were identified in the entorhinal area that have been designated pars medialis and pars lateralis, in accordance with their topographical positions, but both the cytoarchitecture and Neo‐Timm staining pattern are indicative of further subdivision. In pars medialis, the deep half of layer I, the interstices between the stellate cell bodies in layer II, and layer III were medium to heavily stained, whereas layer IV stained weakly. Layers V‐VI were slightly darker than layer IV and were inseparable on the basis of the Neo‐Timm staining. The staining of pars lateralis differed in many respects from that of pars medialis, the most conspicuous feature being a much lighter layer III. In the parasubiculum, the deep half of layer I together with layers II‐III had the appearance of an intensely stained triangle wedged in between the entorhinal area and the presubiculum. The latter showed moderate staining of the inner half of layer I and posterior part of layer II, while layer IV was stained intensely. Layers III and V‐VI exhibited only weak staining.The distribution of zinc in the pig was compared with that in the guinea pig and rat, described previously. Although many histochemical features are shared by the staining patterns of the three species, striking differences exist in the pig, the most notable being the virtually reverse staining of the entorhinal layer IV.The possible functional implications of zinc in synaptic vesicles

ISSN:0092-7317    

DOI:10.1002/cne.902870202

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe dendritic trees of Cb, cholinergic, amacrine cells in the ganglion cell layer of the developing rabbit retina are revealed by intracellular injection with Lucifer yellow to have the adult dendritic branching pattern at birth. It is demonstrated that these cells maintain a constant number of dendritic branches throughout postnatal development and that their dendritic trees increase in size by the growth and subsequent elongation of all branches. Proximal and distal dendrites increase in length by almost the same proportions between birth and adulthood.Although the adult pattern of dendritic branching of Cb amacrine cells is established by birth, dendrities in the young possess numerous short appendages (1–5 μm in length) resembling the “dendritic spines” of immature cat retinal ganglion cells. Some of these structures remain on the dendrites of adult cells but the majority are lost at the end of the third postnatal week. As dendritic spines disappear, the dendrites of Cb amacrine cells, especially the distal portion of the tree, acquire numerous varicosities. At each stage after P10, the gain in the number of varicosities greatly exceeds the loss in spines; this is not consistent with the hypothesis that all varicosities are retracted dendritic spines. The rapid increase in the number of varicosities on distal dendrites of Cb amacrine cells during the first 3 postnatal weeks coincides with the maturation of amacrine cell physiological responses.There is no distinct centroperipheral gradient in the postnatal dendritic maturation (acquisition of varicosities, loss of spines, attainment of the adult number of branches) of Cb amacrine cells from the visual streak to the peripheral retina. However, the area of their dendritic tree increases relatively more in the retinal periphery compared to that in the visual

ISSN:0092-7317    

DOI:10.1002/cne.902870203

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo determine the locations of neurons in the rat brain expressing substance P and neurokinin A mRNA, we performed in situ hybridization with a radiolabeled cRNA probe that was complementary to α‐, β‐, and γ‐preprotachykinin mRNA. Several types of controls indicated specificity of the labeling. Brain regions containing many labeled neurons include the anterior olfactory nucleus, layer II of the olfactory tubercle, the islands of Calleja, the nucleus accumbens, the caudate‐putamen, portions of the amygdala and hypothalamus, the medial habenular nucleus, nuclei of the pontine tegmentum, several raphe nuclei, several portions of the reticular formation, and the nucleus of the solitary tract. Less frequent labeled neurons were also found in many other regions of the brain. These results extend many previous immunocytochemical studies of the locations of neurons containing immunoreactive substance P, neurokinin A, and neur

ISSN:0092-7317    

DOI:10.1002/cne.902870204

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

年代:1989

数据来源: WILEY

摘要:

AbstractMorphological criteria allow several kinds of synapse to be recognized in the vertebrate retina. It is, however, not presently known if, or how, these morphological differences reflect physiological distinctions. Since a proper investigation of synaptic physiology in the intact retina is compromised by technical difficulties, we have examined dispersed cultures to discover if they are likely to provide a more tractable physiological preparation. The chief question addressed here concerns the extent to which normal synaptic development takes place in the impoverished conditions of dispersed cell culture.Cultures were established from embryonic day 8 chick retina and fixed for microscopy on embryonic equivalent (E.E.) days 12, 14, 16, and 18. Neuronal processes appeared shortly after plating and continued to increase in number and extent through E.E. 16. Cone cells were recognizable by virtue of their distinctive oil droplets. Two classes of cone could be distinguished on the basis of the density of their cytoplasmic staining. Presynaptic ribbons could be observed in cone cells on E.E. 12, but characteristic dyad and triad postsynaptic organization was seldom present at this stage nor was it often observed at subsequent times. An increase in the number of ribbon synapses in culture was seen on E.E. 18. These synapses may represent those of bipolar cells. Conventional synapses were found at all times examined but the number of these increased greatly between E.E. 14 and 16. Of these conventional synapses, we found some whose anatomy was characteristic of synapses made by amacrine cells as well as some whose anatomy was characteristic of synapses made by bipolar cells.

ISSN:0092-7317    

DOI:10.1002/cne.902870205

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis study determined the extent of the rostral projection of calcitonin gene‐related peptide‐like immunoreactive (CGRP‐IR) primary afferents in the cat lumbosacral spinal cord. To do this we examined the distribution of CGRP‐like immunoreactivity (CGRP‐LI) contralateral and ipsilateral to multiple dorsal rhizotomies. In the contralateral dorsal spinal cord, CGRP‐IR fibers dwere mostly observed in Lissauer's tract, the dorsal columns, and laminae I, II, and V. Fewer CGRP‐IR fibers were observed in laminae III, IV, and VI and the area around the central canal. The location of the CGRP‐LI suggests that the afferents arose from nociceptors. Unilateral dorsal rhizotomies of five consecutive segments in the lumbar enlargement caused a substantial although incomplete loss of CGRP‐LI in the rhizotomized dorsal spinal cord ipsilateral to the lesions. The majority of the remaining CGRP‐IR fibers were located in Lissauer's tract, the dorsal columns, and the lateral part of laminae I and V. Ventral rhizotomies or an ipsilateral hemisection in the most rostral rhizotomized segment, in addition to the dorsal rhizotomies, had no noticeable effect upon the density or location of the remaining CGRP‐LI. These results suggest that the majority of the CGRP‐LI within the rhizotomized region of spinal cord was contained within branches of small‐diameter primary afferents that entered the spinal cord through intact dorsal roots located caudal to the rhizotomized segments of spinal cord. It is concluded that CGRP‐IR small‐diameter primary afferents are capable of projecting at least five segments beyond their segment of entry and supplying collaterals to the superficial and deeper layers of the dorsal horn involved in the processi

ISSN:0092-7317    

DOI:10.1002/cne.902870206

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe I1 dopaminergic interplexiform cells of the fish retina are believed to modulate horizontal cell coupling by increasing gap junction resistance. Dopamine also modulates the morphology of horizontal cell gap junctions and mimics the effects of light adaptation. To determine whether the light‐dependent changes in gap junction morphology are due to endogenous dopamine release, horizontal cell gap junctions were studied in goldfish retinas lacking dopaminergic neurons.Dopaminergic interplexiform cells were destroyed by intraocular injections of 6‐hydroxydopamine in both eyes. After lesioning, fish were treated in one of four ways: (1) light‐adapted, (2) dark‐adapted (1 hour), (3) light‐adapted and given and intraocular injection of dopamine, or (4) dark‐adapted (1 hour) and injected with dopamine. The effectiveness of lesioning was evaluated by autoradiographic detection of [3H]‐dopamine uptake in the retina of one eye. Retinas in which lesioning of the contralateral eye was deemed effective were processed for freeze‐fracture electron microscopy and the particle density of horizontal cell gap junctions determined.Lesioned retinas, whether light‐ or dark‐adapted, had elevated horizontal cell soma gap junction particle densities compared to lesioned retinas treated with dopamine. These results demonstrate that high soma gap junction particle densities can be correlated with the absence of dopamine and low densities associated with the presence of dopamine. The differences in gap junction particle density between lesioned and lesioned + dopamine‐treatment were similar to differences between nonlesioned dark‐adapted (1 hour) and light‐adapted retinas, respectively. Therefore, the particle density of light‐ and dark‐adapted soma gap junctions suggests a greater release of dopamine in light‐adapted fish than in 1 hour dark‐adapted fish.Gap junctions on axon terminals of horizontal cells in lesioned light‐ and dark‐adapted retinas had reduced particle densities compared to nonlesioned light‐adapted but not to nonlesioned dark‐adapted retinas. However, intraocular injections of dopamine into lesioned eyes did not alter axon terminal gap junction particle densities. This suggests that coupling at the horizontal cell soma and axon terminal

ISSN:0092-7317    

DOI:10.1002/cne.902870207

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo determine the sources and targets of auditory pathways that bypass the inferior colliculus in the mustache bat, we injected WGA‐HRP in the medial geniculate body and related auditory nuclei of the thalamus as well as in the lower brainstem. We used electrophysiological methods to verify that the injection electrode was in an area responsive to sound. The only thalamic injections that produced retrograde transport to cells in auditory nuclei caudal to the inferior colliculus were those that included the suprageniculate nucleus. These injections labeled a group of large multipolar cells lying between the ventral nucleus of the lateral lemniscus and the superior olivary complex. Neurons in this cell group have also been shown to project to the deep layers of the superior colliculus in the mustache bat. The pathway revealed by these studies is almost identical to the “central acoustic tract” in which fibers course medial to the lateral lemniscus and bypass the inferior colliculus to reach the deep superior colliculus and the suprageniculate nu

ISSN:0092-7317    

DOI:10.1002/cne.902870208

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of cholecystokinin (CCK) mRNA in the rat brain was determined by means of in situ hybridization histochemistry. Our results demonstrate a widespread distribution of neurons containing CCK mRNA throughout the rat brain. Hybridization‐positive neurons were distributed throughout the neocortex, olfactory bulb, claustrum, amygdala, the dentate gyrus and hippocampus proper, and several subnuclei of the thalamus and the hypothalamus. The most abundant and most heavily labeled neurons were found in the endopiriform/piriform cortex, tenia tecta, and the ventral tegmental area. The distribution of neurons positive for CCK mRNA paralleled that of CCK‐like immunoreactive neurons. These results detail the distribution of CCK mRNA and clearly identify the existence of CCK‐synthesizing neurons in regions such as the paraventricular and supraoptic nuclei of the hypothalamus, where the presence of CCK cell bodies was previously unce

ISSN:0092-7317    

DOI:10.1002/cne.902870209

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

年代:1989

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902870201

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

年代:1989

数据来源: WILEY