摘要:

AbstractThe purpose of this study was to evaluate by light microscopy the effects of ionizing radiation on spinal cords of rats irradiated when three days of age and killed at intervals up to 28 months after irradiation. The amounts of x‐rays administered (2,000 R; 1,000 R; 500 R) were those which had been demonstrated by short‐term studies in this laboratory to cause either no histopathologic changes or only transient, reparable alterations. The most significant and previously unreported finding was the development, usually restricted to the gray matter, of elongated, spindle‐shaped cells that produce prodigious amounts of fibers clearly demonstrated by the Wilder's reticular stain. In cases where extensive cellular development had occurred, these cells were oriented around the perikarya of the large ventral motor neurons and formed a well‐developed capsule of reticular fibers. This phenomenon occurred more frequently in rats receiving the greater amounts of radiation and killed 12 months or more after exposure. The other observation of interest was the development of lesser amounts of connective tissue‐producing cells in the dorsal gray matter, where these cells were seen initially in the substantia gelatinosa. The significance of these changes is discussed in relation to previously reported long‐term effects of ionizing radiation on the central ner

ISSN:0002-9106    

DOI:10.1002/aja.1001370102

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe innervation to the bronchial tree of the rqt was studied using silver impregnation and methylene blue staining in conjunction with histochemical demonstration of acetylcholinesterase and one‐micron sections of osmium‐bed, plastic‐embedded material. Innervation to the bronchial structures enters the lung along two pathways: (1) in bundles of nerves along the bronchi (peribronchial bundles), and (2) as nerve bundles associated with bronchial arteries (periarterial bundles) to innervate bronchial arteries and respiratory passageways. Fibers within the peribronchial bundles and associated nerve cells contain acetylcholinesterase. Varicose nerve plexuses associated with bronchial muscle (intermuscular nerves) are acetylcholinesterase‐positive, as are the submucosal nerves. Submucosal nerves are of two types. One type originates directly from the peribronchial bundles after passing through the muscularis without innervating it. These nerves extend circumferentially and longitudinally with respect to the bronchiole. The second submucosal nerve type originates from the intermuscular nerve plexus. These nerves have a radial orientation within the bronchial submucosa and reach the mucosa. It is concluded that the intermuscular nerves are postganglionic parasympathetics. The two types of submucosal nerves are thought to perform different fu

ISSN:0002-9106    

DOI:10.1002/aja.1001370103

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

年代:1973

数据来源: WILEY

摘要:

AbstractElectron microscopic, autoradiographic and histochemical techniques were used to determine the distribution of adrenergic and cholinergic nerve fibers within the walls of arterioles having a width of 35 to 60 μ in the hamster cheek pouch. Nerves were confined to the adventitia and their varicose regions were distributed so that 86% were located within 1 μ of the media. Arterioles exposed to3H‐norepinephrine and examined by light microscopic autoradiography exhibited several sites of silver grain accumulation, as a result of the uptake of3H‐norepinephrine by adrenergic nerve fibers. In electron autoradiographs, approximately 70% of all adventitial nerve fibers exhibited silver grains and are therefore considered to be noradrenergic. The majority of all nerve‐associated silver grains were located near the adventitial‐medial junction. Smooth muscle cells sometimes possessed concentrations of silver grains above background levels, perhaps reflecting the capacity of these cells to take up norepinephrine. Acetylcholinesterase activity was demonstrated in 16 to 44% of the adventitial nerve fibers and they are presumed to be cholinergic. Acetylcholinesterase‐stained fibers were distributed throughout the adventitia with 43% being located closer than 1 μ to the media. The morphological identification of a dual adrenergic and cholinergic innervation of arterioles of the hamster cheek pouch indicates the probable presence of an active as opposed to a passive vasodilato

ISSN:0002-9106    

DOI:10.1002/aja.1001370104

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe hippocampal formation of newborn mice was explanted and maintained in Maximow culture assemblies for up to 35 days. At the time of explantation, only the suprapyramidal limb of the dentate gyrus was cytoarchitectonically distinct, and electron microscopy of newborn hippocampus revealed no definitive synapses. Histogenesis, as indicated by the development of the infrapyramidal limb of the dentate gyrus, and synaptogenesis, as indicated by the in vitro formation of mossy fiber synapses on the dendrites of hippocampal pyramidal neurons were studied by light and electron microscopy. At 12 days and thereafter in culture, mossy fiber terminals were found in synapsis with dendritic spines probably belonging to pyramidal cells of the hippocampal zone CA4. Near dentate granule cell somata a few axosomatic and many axospinous and axodendritic synapses were found. The data indicate that granule cells of the developing dentate gyrus are capable of differentiation in vitro into a structure essentially equivalent to that developed in vivo. The granule cells may become arranged into a recognizable granule cell layer, and develop dendritic processes which receive synapses virtually identical to those found in the intact organ. The differentiation of these features proceeds in the absence of the extrinsic afferents from the septum or from the contralateral hippocampal formation.

ISSN:0002-9106    

DOI:10.1002/aja.1001370105

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to obtain information about factors controlling the interkinetic movement of neuroepithelial cells and the cortical migration of neuroblasts in the developing mouse neocortex. In the first experiment 15‐day pregnant mice were injected with a single dose of fluorodeoxyuridine, a compound which inhibits the enzyme thymidylate synthetase thus blocking DNA‐replication. The animals were sacrificed at various hours and days following treatment. Two hours after treatment the mitotic index of the neuroepithelial cells was severely reduced and cells with abnormal nuclei appeared in the DNA‐synthesizing zone of the neuroepithelial layer. By five hours more abnormal cells appeared and many showed degenerating nuclei. By 12 hours cells with abnormal nuclei were seen in the outer half of the neuroepithelial layer and some in the migratory zone. Since they were not seen at the lumen, these observations indicate that fluorodeoxyuridine‐affected nuclei do not move to the lumen and do not divide. By 24 hours abnormal nuclei were seen in the migratory zone and cortical plate suggesting cortical migration without preceding cell division. In the second experiment 15‐day pregnant mice were treated with col‐cemid, a compound which arrests dividing cells in metaphase. Two and four hours after injection a large number of neuroepithelial cells in metaphase accumulated at the lumen. By seven and 12 hours the number of arrested metaphases decreased rapidly, but at the same time cells with dense, darkly stained nuclei appeared in the adjacent neuroepithelium. By 24 hours these abnormal nuclei were present in the migratory zone and cortical plate, suggesting that they were migrating towards the surface of the cortex despite the failure to complete mitosis. In the third experiment 15‐day pregnant mice were injected with bromodeoxyuridine, a compound incorporated into DNA and thought to interfere with differentiation. During the first 12 hours after treatment a striking increase in the number of normal mitotic figures was seen at the lumen. By 16 hours, however, abnormal mitotic figures started to appear. Since the generation time of neuroepithelial cells at this stage of development is about 13 hours, the abnormal mitotic figures must represent cells which have gone through two DNA‐synthetic periods since the beginning of the treatment. The abnormal mitotic figures give rise to cells with dense pycnotic nuclei which by 24 hours are found throughout the width of the developing neocortex. Thus in each experiment cells with abnormal, presumably non‐functional, nuclei were produced. Despite the failure to divide or to carry out a normal division, the nuclei migrate from the neuroepithelial layer towards the cortical plate in a fashion similar to that of normal postmi

ISSN:0002-9106    

DOI:10.1002/aja.1001370106

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe first goal of this investigation was to determine the time of origin of Purkinje cells and their final location in the various lobes of the cerebellum. DUB/ICR mice were therefore injected with several doses of3H‐thymidine on day 11, 12, 13, 14, or 15 of gestation. Cells formed on days 11 and 12 appeared in all lobes of the postnatal vermis but those formed on day 13 became located mainly in the anterior lobe.The second goal was to examine the effect of 5‐fluorodeoxyuridine, a DNA synthesis inhibitor, on Purkinje cell formation and on repair of the rhombic lip after a prenatal trauma. Five hours after treatment with fluorodeoxyuridine cells with darkly stained nuclear clumps appeared and mitotic activity ceased. Twelve hours after treatment mitotic activity remained low and more affected cells appeared in the neuroepithelium of the rhombic lip. By 24 hours abnormal cells had disappeared, mitotic activity was almost normal and the neuroepithelium had regained its regular continuity. Treatment on day 12 led to a significant deficit of Purkinje cells in all lobes of the vermis, while treatment on day 13 caused a deficit in the anterior lobe only. Despite the postnatal Purkinje cell deficit, compensatory cell proliferation had occurred in the rhombic lip. The mitotic index in the treated embryos reached the value of the controls after 24 hours and was extremely high after 48 hours. Part of this proliferative activity leads to Purkinje cell production, for it was possible to label substantial numbers of Purkinje cells on day 14 of gestation in animals treated with fluorodeoxyuridine on day 12, while control animals have virtually completed Purkinje cell formation by day 14. Although Purkinje cell deficits were accompanied by a reduction in the size of the cerebellum, the cytoarchitecture of the cerebellum appeared nor

ISSN:0002-9106    

DOI:10.1002/aja.1001370107

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe ultrastructural and cytochemical properties of the maxillary gland were investigated in 24 adult Sprague‐Dawley rats of both sexes. The relationship between the interstitial cell and/or excitatory cholinergic terminals with the secretory cell was discussed. The secretory material containing primarily neutral lipids, proteins, carbohydrates and mucosubstances appeared electron‐opaque following staining with uranyl acetate and lead citrate. Ruthenium red precipitated strongly on zymogenic granules which showed an increasing affinity for phosphotungstic acid, paralleling a rise in pH towards 7.7. The process of fusion of the plasma membrane with the membrane of secretory granules was observed, although some membrane‐bound granules were identified in the acinar and ductal lumina. Intracellular membranous structures were best revealed with phosphotungstic acid at pH 1.0–1.5, whereas ruthenium red reacted primarily with lipid inclusions and tonofilaments. Acid phosphatase activity was predominantly limited to secondary lysosomes and, to a lesser degree, to primary lysosomes and Golgi saccules. The morphological and chemical properties of secondary lysosomes in the secretory cell suggested a pronounced hydrolytic activity related to lipid inclusions and endocytotic v

ISSN:0002-9106    

DOI:10.1002/aja.1001370108

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

年代:1973

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001370101

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

年代:1973

数据来源: WILEY