摘要:

AbstractThe neuronal population of the PAG consists of relatively small cells, ranging from approximately 8 μ to 30 μ in diameter. These neurons are of three different types and are classified as I, II, and III for the sake of convenience. Each class aggregates in certain areas of the central gray to form subdivisions distinguishable by differing neuronal distributions as well as by cellular characteristics. Class I neurons are small, spindle shaped cells that stain darkly with cresyl violet. They aggregate loosely around the cerebral aqueduct, thus forming the comparatively acellular inner ring of the PAG, the nucleus medialis. The class II cells are also small and darkly staining, but they are fusiform to spherical in shape. These cells cluster more closely and are surrounded by many glial cells. They congregate in the area dorsal to the cerebral aqueduct to form the nucleus dorsalis. The largest cells of the PAG, the class III neurons are spherical or tringular in shape and stain lightly due to their sparse Nissl substance. Frequently glial cells abut the perikaryon of these neurons. They aggregate very closely to form the dense cellular outer portion of the PAG. This mantle of cells is called the nucleus laterali

ISSN:0092-7317    

DOI:10.1002/cne.901490102

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

年代:1973

数据来源: WILEY

摘要:

AbstractRetrograde degeneration in thalamus was studied in eight Macaque monkeys following resection of basomedial temporal cortex. In addition to its known projection to the posterior cingulate region, nucleus lateralis dorsalis (LD) projects, perhaps via the fornix, to the parahippocampal gyrus. Convexal temporal neocortex receives fibers from the medial pulvinar (PM). Nucleus lateralis posterior (LP) may project to cortex intervening between the projection fields for LD and PM. A stereotactic lesion in fornix of one animal demonstrates corticothalamic projection to LD, LP and to a lesser extent to PM, AV, AM, and AD.

ISSN:0092-7317    

DOI:10.1002/cne.901490103

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe staining of half‐micron thick Epon sections with toluidine blue provides a reliable method for the identification of glial cells. The diagnostic features of these cells observed in thecorpus callosumof one‐month‐old rats are as follows: (1)Astrocyteshave a very pale nucleus and cytoplasm; the nuclear envelope is sharply outlined by a thin chromatin lining with occasional chromatin beads; (2)Microgliahave a small nucleus in which large, dark chromatin masses contrast with the nucleoplasm; the nucleus is round or elongated, and may be somewhat angular. The pericytes, which have a similar but usually crescentic nucleus, may be related to microglia. (3)Oligodendrocytesvary from pale to very dense and may be arbitrarily classified into three subgroups: Thelight oligodendrocytesare large pale cells with round to ovoid nucleus containing a prominent nucleolus and little or no condensed chromatin; the cytoplasm is extensive and appears pale, although less so than the nucleus. Themedium shade oligodendrocytesare smaller cells that have an ovoid nucleus carrying small chromatin clumps and appearing moderately basophilic throughout; the cytoplasm is less extensive and somewhat darker than in the “light” subgroup. Thedark oligodendrocytesare usually smaller than medium shade cells and often have an indented or angular nucleus with large chromatin masses; both nucleoplasm and cytoplasm are densely stained; the cytoplasm is often scanty and accumulated on one side of the nucleus.Semithin sections of thecerebral cortexshow glia with similar features, with the exception of the astrocytes, which have a smaller but more basophilic cytoplasm than in corpus callosum.The cells of thesubependymal layerof the lateral ventricle, when examined in semithin sections in the neighborhood of the corpus callosum, display a patchy, irregular nucleus and a scanty cytoplasm. Similar cells with a more regular nucleus are found outside the layer and in the corpus callosum; they are designatedfree subependy

ISSN:0092-7317    

DOI:10.1002/cne.901490104

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

年代:1973

数据来源: WILEY

摘要:

AbstractSemithin Epon sections stained with toluidine blue were used to enumerate astrocytes, microglia, the three subtypes of oligodendrocytes, and cells referred to as free subependymal cells, in the corpus callosum and cerebral cortex of male Sherman rats of various ages. The period covered extended from a few days before weaning (3/4 month of age) until the time when growth became negligible (5 months of age).The total number of glial cells increases with age in both cortex and corpus callosum. However, the investigation of individual cell types reveals that the number ofmicrogliaremains fairly constant throughout the period under study. The number ofastrocytesin corpus callosum increases up to the age of one month, but remains constant thereafter, while their number in the cortex is the same at all investigated times. In the case ofoligodendrocytes, the three subtypes behave differently. About two‐thirds of the oligodendrocytes in rats aged three‐quarters of a month are of the light or medium shade types, but the number of these gradually decreases with age and becomes very low in five‐month‐old rats. In contrast, the dark cells which constitute about one‐third of the oligodendrocytes in young rats make up nearly the whole of this group in adults. Finally,free subependymal cellsare absent in cortex throughout the period under study, but are present in corpus callosum, where their number steadily declines with age.In conclusion, the numbers of astrocytes and microglia seem to remain constant in growing rats after the age of one month. Dark oligodendrocytes markedly increase in number with age, while the other types of oligodendrocytes and the free subependymal cells are reduced to negligible numbers by the age of fi

ISSN:0092-7317    

DOI:10.1002/cne.901490105

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

年代:1973

数据来源: WILEY

摘要:

AbstractStrong labeling of the cells in the subependymal layer was produced by stereotaxic injection of 5 μCi of3H‐thymidine into the left lateral ventricle of the brain of one and a quarter month old rats weighing about 100 gm. These animals were sacrificed by glutaraldehyde perfusion from two hours to 21 days later. Blocks of corpus callosum with adjacent subependymal and ependymal layers were excised from the injected and non‐injected sides, and embedded in Epon; 0.5 μ thick sections were radioautographed and stained with toluidine blue.In the subependymal region, on both injected and non‐injected sides, there was an immediate uptake of label by many cells followed by an increase and later a decrease in the percent cells labeled. In the corpus callosum while at first the percent labeling of glial cells was rather low, it did increase slowly with time and, after seven days, exceeded that in the subependymal region. These results were interpreted as indicating that cells arising in the subependymal layer had migrated into the corpus callosum.Up to four days after injection, most of the label in corpus callosum was present in immature‐looking cells resembling the cells of the subependymal layer and referred to asfree subependymal cells.With time, the percent labeling decreased in these cells while increasing in some of the glial cells. A labeling peak was observed for lightoligodendrocytesat four to seven days and for dark oligodendrocytes at 21 days, whereas labeling of medium shade oligodendrocytes occurred at intermediate times. The succession of labeling peaks indicated a sequence of development from free subependymal cells through light and medium shade to dark oligodendrocytes. Fewastrocytescarried label at any time; those which did seemed to have arisen from the transformation of labeled free subependymal cells.Microgliawere unlabeled at two hours, but their percent labeling was high at 4–14 days. While the labeling of other glial cells reflected their physiological behavior, the labeling of microglia was a consequence of the trauma produced by the injection 0f tracer into the ventricle.In conclusion, cells coming from the subependymal layer appear to migrate into the corpus callosum where, in 100 gm rats, many of them transform into oligodendrocytes and a few into

ISSN:0092-7317    

DOI:10.1002/cne.901490106

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe topographic organization of spinal afferents to the lateral reticular nucleus (LRN) has been reexamined in 34 adult cats. Two modifications of the Nauta technique were used to show secondary terminal degeneration resulting from circumscribed lesions at various levels of the spinal cord. The results demonstrate that the “inner segment” of LRN corresponding roughly to Brodal's magnocellular portion, receives fibers from spinal segments C1–D3, while the “outer segment” corresponding approximately to Brodal's parvocellular protion receives fibers from spinal levels below L3. The “middle segment” — a transitional zone between the two former portions — represents the spinal segments D4–L3. The ascending fibers terminate predominantly on the ipsilateral side; only few degenerated elements are noted within the contralateral nucleus. The subtrigeminal portion does not seem to receive afferent fibers from the spinal cord. This finding raises the question of nomenclature, which is briefly discussed in the light of the classical “nucleus funiculi lateralis” concept. Finally, the present data are consistent with electrophysiological data of Oscarsson, Rosén and collaborators according to which LRN represents spinal levels of convergent inputs from large as well as bilateral receptive fields rather than somatotopically arranged projections from

ISSN:0092-7317    

DOI:10.1002/cne.901490107

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe neocortical surface of the rabbit's brain was explored by macroelectrodes with isolated electrical stimulation of the vestibular nerve. Surface positive evoked potentials were recorded within the first somatosensory (SI) forelimb field. Negative field potentials in middle cortical layers were only found in a small area within the rostral part of this field. The rabbit's vestibular field is compared with those of rodents, carnivores and primates.

ISSN:0092-7317    

DOI:10.1002/cne.901490108

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901490101

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

年代:1973

数据来源: WILEY