摘要:

AbstractThe junctional complex of the choroidal epithelium of the adult domestic fowl consists of three characteristic components—thezonula occludens, zonula adherensandmacula adherens.The quintuple‐layeredzonula occludens(tight junction) occupies a juxtaluminal position and extends in depth from 0.2–0.4 μ. As a consequence of the intimate fusion of the outer leaflets of the apposed cell membranes, the tight junction is void of any discernible intercellular space. Thezonula adherensnormally varies in depth from 0.35–0.55 μ. Moderate to heavy accumulations of fibrillar and granular cytoplasmic material occur adjacent to the inner leaflets of the apposed cell membranes. These dense, cytoplasmic bands mesh with fibrillar elements of the general cytoplasm. The intercellular space of the intermediate junction is frequently attenuated by constrictions in the cell membranes. The tight and intermediate junctions appear to form continuous belts encircling each epithelial cell. Themacula adherens(desmosome) is not especially well developed, usually lacking well developed cytoplasmic plaques.The early development of thezonula occludensis marked by the convergence of the apposed cell membranes, starting first at a localized point at or near the basal margin of the presumptive tight junction. Subsequently, convergence occurs at one or a few additional points, often near the middle of the developing tight junction. Finally, preparatory to membrane fusion, the adjacent cell membranes are brought into close apposition throughout the linear extent of the tight junction. Membrane fusion usually commences at or near the lower margin of thezonula occludens, in the area of initial membrane convergence, and then proceeds toward the luminal border.With the onset of membrane convergence, a network of fine fibrillar and granular cytoplasmic material accumulates adjacent to the inner leaflets of the apposed cell membranes. This cytoplasmic development subsides in the tight junction subsequent to membrane fusion but persists in moderate to dense accumulations in the other areas of the junctional complex. Numerous other associated events occurring during the differentiation of the junctional complex are discussed

ISSN:0092-7317    

DOI:10.1002/cne.901360302

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

年代:1969

数据来源: WILEY

摘要:

AbstractIn one experiment rats were injected with single does of thymidine‐H3at 6 hours, 2, 6 and 13 days of age, or with multiple doses during two periods of early life, and were killed when 2, 4 and 6 months old. In the autoradiographic analysis attention was focused on the time of origin and differentiation of basket, stellate and granule cells in different regions of the cerebellar cortex. In another, non‐radioactive study, in rats ranging in age from newborn to adult, the development of the cerebellum was studied with quantitative and qualitative histological techniques.In the sagittal plane the area of the cerebellum increases over 20‐fold from birth to 21 days. This increase is primarily due to the growth of the cerebellar cortex, much of the increment in the area of the subcortical regions occurring after 21 days. During the first week the growth of the different layers, excepting the proliferative external granular layer, is sluggish. During this period, the cells of the external granular layer do not differentiate but provide stem cells to this growing proliferative matrix. These proliferating and migrating cells of the external granular layer are the precursors of the basket, stellate and granule cells of the cortex; glia cells probably arise from cells multiplying locally. The first cells to differentiate are situated in the lower half of the molecular layer and include basket cells. Stellate cells differentiate later, with a peak at the end of the second week. The bulk of granule cells differentiate during the second and third weeks, with 25–80% of them, depending on the region, being formed between 11–21 days. These differences, together with several histological criteria (thickness of external granular and molecular layers, appearance of Purkinje cells) were used for constructing regional developmental maps of the cerebellar cortex. Granule cells differentiate in the depth of vermian fissures before they do over the exposed surfaces of the lobes; the ventral lobes (lingula and nodulus) mature before the anterior lobes; and the last maturing vermian lobes are the tuber, declive and culmen. The hemispheres, with some exceptions, mature later than the vermis, with the paraflocculus being among the last maturing s

ISSN:0092-7317    

DOI:10.1002/cne.901360303

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe organization in the cat of the projection of the visual field onto the medial part of the central half of dorsal lateral geniculate nucleus (LGNd), the medial interlaminar nucleus (MIN) and the posterior nucleus of the thalamus (PN) has been studied by systematically plotting the receptive fields of single units isolated in the nuclei by tungsten microelectrodes. Using a grid of verticals (azimuth) and horizontals (elevation), projection maps were prepared by locating the recording sites of the units in serial histological sections. We have plotted three separate but related topographical projections of the visual field, one in each nucleus. Particular attention was paid to the projection of the visual axis in the LGNd. With the possible exception of the upper periphery, the whole of the visual field is represented in the MIN, the topographical organization with respect to azimuths being the mirror‐image of that in the LGNd. There were very few binocularly activated units in the MIN and no evidence was found of a laminar segregation of crossed and uncrossed optic tract terminals. The topographical projection onto the PN resembled that in the MIN except that the upper visual field was even more restricted and the organization of azimuth values was again reversed such that the central visual field projected inferomedially and the peripheral field dorsolaterally. In all three nuclei a naso‐temporal overlap was found with receptive fields located across the midline in the ipsilateral hemifield for about 2° in the case of LGNd units and 6° or more in the case of the MIN and PN. Some observations are made on visually active units in the lateral posterior nucleus of the thalamus and the pulvinar, many responding binocu

ISSN:0092-7317    

DOI:10.1002/cne.901360304

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

年代:1969

数据来源: WILEY

摘要:

AbstractThere is a system of highly specialized blood vessels around each sensory hair follicle in the rabbit. The system includes two arteriovenous shunts and a cylinder of dilative blood vessels enclosed in a large bulbous capsule of connective tissue. The shunts, dilative blood vessels and capsule surround two cylinders of nerve fibers; together these structures constitute the largest neurovascular end‐organ in skin. The end‐organ is similar to the glomus‐Pacinian corpuscle complex in the hairless digital skin of man.The blood vessel cylinder and arteriovenous shunts in rabbit skin connect with a system of dilative blood vessels that are enclosed in another capsule of connective tissue under a small thick pad of sensory epidermis, beihnd the sensory hair follicle. The pad of epidermis contains expanded nerve fibers (Merkel's discs) that end near a cluster of Merkel (tactile) cells. In some regions of skin, each area of sensory epidermis is associated with the orifice of a sweat gland duct.In hairy skin of the rabbit, mouse and sheep, the areas of sensory epidermis, Merkel cells and Merkel's discs are distributed in parallel chains or in whorls and loops. Similarly, in the hairless skin of man the sensory epidermis, clusters of Merkel's discs and sweat duct orifices are distributed together in rows, whorls and loops that form the finger and palmer prints. In some regions of hairy human skin the same components occur together in small circular whorls called theHaarscheibenorRos

ISSN:0092-7317    

DOI:10.1002/cne.901360305

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe efferent projection fibers from the olfactory bulb have been studied using the Nauta‐Gygax and the Fink‐Heimer methods for degenerating axons after lesions were suitably placed by thermo‐coagulation. From the olfactory bulb efferent fibers by way of the ipsilateral lateral olfactory tract end as preterminal and terminal fibers in the lateral, the external and the ventral segments of the anterior olfactory nucleus; the lateral two‐thirds of the lateral olfactory tract, the cortical and the medial nuclei of the amygdaloid

ISSN:0092-7317    

DOI:10.1002/cne.901360306

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe 34 ganglia of the leech (Hirudo medicinalis) central nervous system together with their connectives and roots have been studied by means of the fluorescence histochemical technique for monoamines.More than half the ganglia of the central nervous system possess the same number of monoamine‐containing neurons in a fixed location. These identical ganglia consist of seven yellow fluorescent monoamine‐containing neuron perikarya located within the ganglia and a pair of blue‐green fluorescent monoamine‐containing perikarya located outside the ganglia in the anterior roots. A neuropile consisting of a dense network of yellow and blue‐green fluorescent varicose processes, several smooth blue‐green fluorescent processes and occasional smooth yellow fluorescent processes is present in the ganglia. Smooth and varicose yellow and blue‐green fluorescent processes are found in the connectives and roots of the ganglia. The intraneuronal distribution of fluorescence within the nine monoamine‐containing neurons of identical ganglia is described.The monoamine‐containing neurons of the remaining ganglia of the central nervous system are described. These ganglia are shown to vary only slightly from the pattern of

ISSN:0092-7317    

DOI:10.1002/cne.901360307

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

年代:1969

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901360301

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

年代:1969

数据来源: WILEY