Ferenc Hajós

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain. I. Forebrain.

SummaryIn the first of two papers dealing with the distribution of glial fibrillary acidic protein-(GFAP)-immunoreactive elements in the rat brain, the localization of immunostaining in the forebrain is systematically described. While the limbic cortex was found to contain intensely stained, evenly distributed astrocytes, the neocortex showed clearly stratified GFAP-staining, with substantially less immunoreactivity occurring in the middle layers than in the areas close to the brain surface or the white matter. A remarkably regular staining pattern was observed in the hippocampus and dentate gyrus. The striatum remained unstained in sharp contrast to the pallidum. In the diencephalon, the main thalamic nuclei were poor in GFAP-labelled elements in contrast to the internuclear border zones. In the hypothalamus, nuclei were conspicuous by their GFAP-staining. A consistent differential staining pattern was obtained in the epithalamic structures. The observed distributional pattern of diencephalic GFAP-immunoreactivity is thought to be due to different regional proliferation of the embryonic neuroepithelium of the diencephalon. The uneven distribution of GFAP-immunoreactivity in the forebrain is explained on a mainly developmental basis.

Immunohisto- and cytochemical localization of cortical nicotinic cholinoceptors in rat and man.

A monoclonal antibody (WF 6) raised against purified Torpedo nicotinic acetylcholine receptor was applied to study the cellular and subcellular receptor distribution in human and rat neocortex. In both species, immunostaining was most prominent in perikarya and dendrites of the projection neurons in layers III and V. In layer VI fusiform cells displayed immunoreactivity while in layers I, II and IV some round-shaped cells were immunostained. Subcellularly, immunoprecipitate was found in neuronal perikarya, dendrites and in the postsynaptic thickenings, indicating intracellular sites of synthesis, transport and membrane incorporation of receptor protein. The results suggest that WF 6-immunocytochemistry is a useful tool to label nicotinic cholinergic receptors rendering new information about the specific cell-type and subcellular receptor distribution hardly obtainable by using conventional receptor autoradiography.

Radial glia in the developing mouse cerebral cortex and hippocampus.

SummaryThe regional distribution of radial glia in the developing cerebral cortex and the hippocampus of the mouse was studied using silver impregnation and immunocytochemical staining for glial fibrillary acidic protein (GFAP). Whilst the former technique revealed radial fibres at a slightly earlier age, immunocytochemistry gave a better picture of their general distribution and enabled systematic study of the appearance and disappearance of GFAP-positive radial glia throughout the cortex. Although a clear association between migrating neurones and radial glia was evident in the later stages of cortical plate formation, this relationship was not apparent in all cortical regions nor at the very early stages of the formation of the cortical plate. Even after allowing for a delayed appearance of GFAP immunoreactivity in relatively mature radial glia, the uneven distribution of these cells, their appearance after the cortical plate has already been formed, and their regional development in a pattern dissynchronous with that of the cortical plate argue against a general role of these structures in neuronal migration in the mouse, although there are notable phylogenetic differences.

Immunocytochemical demonstration of glial fibrillary acidic protein in mouse tanycytes

SummaryImmunohistochemical techniques were used to stain for the astrocytespecific glial fibrillary acidic protein (GFAP) in the cells lining the third ventricle of the developing and mature mouse brain. Before birth immunoreactive tanycytes were only observed in the infundibular recess of the median eminence, where they could first be seen at embryonic day 17. They possessed long processes running towards the ventral surface of the brain. During the early postnatal period GFAP-positive tanycytes gradually appeared throughout the third ventricle, although the ependymal cells themselves remained unstained. The tanycytes retained their immunoreactivity for anti-GFAP serum in the adult, and were also evident in the adult rat third ventricle. It is suggested that the presence of GFAP in these specialised cells of the third ventricle indicates that they, the transient radial glia of the developing cerebral cortex, the persistent Bergmann glia of the cerebellum, similar astrocytes with radial processes in the hippocampal dentate gyrus and conventional astroglia are all closely related cell types.

NEUROGLIA IN THE INTERNAL GRANULAR LAYER OF THE DEVELOPING RAT CEREBELLAR CORTEX

Neuroglia in the internal granular layer of the developing rat cerebellar cortex

Types and spatial distribution of vasoactive intestinal polypeptide (VIP)-containing synapses in the rat visual cortex

SummaryIn the rat visual cortex vasoactive intestinal polypeptide (VIP)-containing structures were studied by means of light and electron microscopy and image analysis. VIP-immunoreactive axon terminals were found to form symmetric synapses with small dendritic shafts, dendritic spines and somata of pyramidal cells and interneurons. VIP-terminals often occured in pairs with VIP-negative, asymmetric synapses on the same postsynaptic structure. VIP-immunostained dendrites and perikarya were contacted by a purely asymmetric and a mixed population of VIP-negative terminals, respectively. Synaptic connections between two VIP-neurons are seldom as compared to the other types of VIP-synapses. Quantitative studies obtained by the image analysis of VIP-stained boutons and dendritic particles in light microscopic preparations suggest a distinct laminar distribution. Dendritic particles are most frequent in layers I–II, whereas axonal boutons have three laminar accumulations: at the border of layers I–II, in layer IV and layer VI. Together with previous results, the present findings argue for a non-random spatial distribution of VIP-boutons.

The surface-contact glia.

1 General Introduction.- 1.1 Brief History.- 1.2 Development of the Glia: Current Views and Problems.- 2 Materials and Methods.- 3 Postnatal Cell Proliferation at Nongerminal Sites of the Brain.- 3.1 Introductory Remarks.- 3.2 Mitotic Activity at Nongerminal Sites of the Immature Cerebellar Cortex.- 3.3 Mitotic Activity at Nongerminal Sites of the Immature Forebrain: Time Course and Regional Distribution.- 3.4 Comments.- 3.4.1 Cerebellum.- 3.4.2 Forebrain.- 3.5 Light and Electron Microscopic Description of [3H] Thymidine-Labeled Cells at Nongerminal Sites of the Postnatal Brain.- 3.5.1 Light Microscopic Autoradiography.- 3.5.2 Electron Microscopic Autoradiography.- 3.6 Comments.- 3.6.1 Cerebellum.- 3.6.2 Forebrain.- 4 Radial Glia in the Pre- and Postnatal Brain.- 4.1 Introductory Remarks.- 4.2 GFAP Immunocytochemistry of the Developing Forebrain.- 4.2.1 Cerebral Cortex.- 4.2.2 Hippocampus and Dentate Gyrus.- 4.2.3 Diencephalon.- 4.3 Silver Impregnation of the Forebrain Radial Glia.- 4.4 Comments.- 5 Demonstration of Proliferative Capacity of the GFAP-Immunoreaetive Radial Glia.- 5.1 Introductory Remarks.- 5.2 [3H]Thymidine Uptake into the GFAP-Immunopositive Radial Glia.- 5.3 Comments.- 6 Transport of Material by Glial Processes.- 6.1 Introductory Remarks.- 6.2 Transport of HRP by the Forebrain Radial Glia and Cerebellar Bergmanu Glia.- 6.2.1 Transport in the Forebrain.- 6.2.2 Transport in the Cerebellum.- 6.3 Comments.- 7 Discussion.- 7.1 Proliferating Cells at Nongerminal Sites in the Early Postnatal Period.- 7.2 Persistence of the Radial Glia.- 7.3 Does Postnatal Glial Proliferation Involve Dormant Stem Cells or the Differentiated Glia?.- 7.4 Derivatives of and Mechanism of Derivation from the Radial Glia.- 7.4.1 Astrocytes.- 7.4.2 Cerebellar Bergmann Glia.- 7.4.3 Diencephalic Tanycytes and Retinal Muller Cells.- 7.5 Common Properties of Radial Glial Derivatives.- 7.5.1 Capability of Transporting Material Between Various Brain Fluid Spaces.- 7.5.2 Guidance of Neuronal Migration.- 7.5.3 Morphological Similarities.- 8 Concept of the Surface-Contact Glia.- 9 Current Approaches to the Glia and Some Perspectives.- 10 Summary.- 11 References.- 12 Subject Index.

Proliferation of bergmann-glia in the developing rat cerebellum

SummaryMitotic cells in the ganglionic layer of the infant rat cerebellum were studied between 3 to 12 postnatal days. The connection of these cells with the radial glial fibers of the primitive molecular layer could be established. On this basis it was assumed that the mitotic cells studied were immature Bergmann-glial cells whose proliferative activity seemed to continue even after the formation of their characteristic radial fibers. This phenomenon might offer an explanation for the divergent views on the generation time of Bergmann-glia.

The demonstration of immunoreactive dystrophin and its developmental expression in perivascular astrocytes

Immunoreactivity of dystrophin family proteins was observed in the astrocytes of the adult and immature rat hippocampus and cerebral cortex by using Dys2, a monoclonal antibody recognizing both 427 kDa and short dystrophin isoforms. As revealed by light and electron microscopy, immunostaining of the ribosomal apparatus and of pericapillary endfeet was particularly pronounced in the adult. In the pericapillary astrocyte processes immunostaining appeared between postnatal days 10 and 20, and reached the intensity seen in the adult by postnatal day 30. In the pericapillary astrocyte process, the membrane facing the endothelial basal lamina was the earliest structure to show the immunoreaction. At later stages, the pericapillary astrocyte process was gradually filled up with immunoprecipitate. Findings suggest that dystrophins are expressed coinciding with the development of the blood-brain barrier, and it is assumed that they contribute to the formation of this system.

Alterations in glial fibrillary acidic protein immunoreactivity in the upper dorsal horn of the rat spinal cord in the course of transganglionic degenerative atrophy and regenerative proliferation

Transection of a peripheral nerve induces marked increase in the glial fibrillary acidic protein (GFAP) immunoreactivity in the ipsilateral, segmentally related upper dorsal horn. Increase of GFAP immunoreaction is similar to, but not identical with, that observed after dorsal rhizotomy. If the peripheral nerve succeeds in regenerating, GFAP immunoreactivity in the upper dorsal horn returns to normal. It is concluded that the amount and distribution of GFAP is determined by transganglionic degenerative atrophy. Wallerian degeneration and regenerative proliferation of dorsal root axon terminals, respectively.