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PubMed1994

The development of the radial glial scaffold of the cerebellar cortex from GFAP-positive cells in the external granular layer.

We have reinvestigated the origin and genesis of the radial glia of the cerebellar cortex in the hamster using three astroglial markers, vimentin, GFAP, and S-100 protein antibodies. On embryonic day 12 (E12), before the emergence of the external granular layer, the cerebellar anlage is traversed from the ventricle to the pial surface by a primordial radial glial scaffold which is vimentin-positive, but GFAP and S-100 negative. With the formation of the external granular layer on E13, a few GFAP positive cells appear among the unstained external granular layer cells. First seen within the germinal trigone and caudalmost part of the external granular layer, they then develop rostrally, amongst the cells of the expanding external granular layer, proliferating adjacent to the basement membrane. Beginning on E15, cells that are positive for the S-100 protein also appear within the external granular layer and the molecular zone. In later stages, S-100 is strongly expressed in Golgi epithelial cells, so we have considered it to be a marker for these cells. By contrast, the primordial radial glial cells were not stained with this marker. On the day of birth (E16/PO) many S-100 positive cells also appear at intermediate levels between the EGL and the Purkinje cell plate. They are unipolar and bear a single radial process that is directed towards the pial surface. The caudorostral appearance of S-100-positive cells firstly in the external granular layer, then in the molecular zone and finally in the Purkinje cell plate is identical to the temporal sequence of development of these layers, and suggests that S-100-positive cells are at first integral constituents of the external granular layer, but later descend through the molecular zone, to colonize the Purkinje cell plate. Here they proliferate and ultimately differentiate into Golgi epithelial cells, their numerous short radial glial processes traversing the molecular zone and the external granular layer to fill the interstices between the primordial radial glial fibres. At birth, S-100-positive Golgi epithelial cells have progressively colonized the Purkinje cell plate from the germinal trigone rostrally, up to a region midway between primary fissure and anterior medullary velum and, between P2 and P3, the rostralmost part of the cerebellum has become populated. GFAP- and S-100-positive cells remain in the external granular layer up to the end of the first postnatal week. In the same interval, the number of Golgi epithelial cells and Bergmann glial fibres increases rapidly in the expanding cerebellar cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Onset of Tlx-3 expression in the chick cerebellar cortex correlates with the morphological development of fissures and delineates a posterior transverse boundary.

Recent studies have shown that the mammalian cerebellar cortex can be subdivided into a reproducible array of zones and stripes. In particular, discontinuous patterns of gene expression together with mutational analysis suggest that there are at least four distinct transverse zones along the rostrocaudal axis in mouse: the anterior zone (lobules I-V), the central zone (lobules VI and VII), the posterior zone (lobules VIII and IX), and the nodular zone (lobule X). Here we show that the divergent homeobox-containing transcription factor, Tlx- 3 (also known as Hox11L2 or Rnx) is transiently expressed in external granule cells in a distinct transverse domain of the developing chick cerebellar cortex. Expression is first detected at Hamburger and Hamilton (HH) stage 35. Interestingly, Tlx-3 mRNA expression is initially confined to, and coincident with, the morphological development of fissures. Slightly later, at HH stage 38, expression extends throughout the developing external granular layer (EGL) of lobules I-IXab. Notably, no Tlx-3 expression was detected in lobules IXc and X at any developmental time point examined. Expression is noticeably stronger in nonproliferating cells located in the deep layer of the EGL. Tlx-3 expression is downregulated as granule cells migrate inward to form the internal granule layer and is undetectable shortly after birth. These results suggest that Tlx-3 is expressed as granule cells become postmitotic and suggest that Tlx-3 may play a role in the differentiation of distinct neuronal populations in the cerebellum.

Animals↗
PubMed2000

Postnatal development of unipolar brush cells in the cerebellar cortex of cat.

The postnatal developmental distribution pattern of metabotropic glutamate receptor (mGluR1a) immunoreactive unipolar brush cells (UBCs) was studied in the cerebellar cortex of kittens. On the day of birth (P0) UBCs are already present in the white matter in lobule X of the vermis, but only a few of these cell seemed to migrate to the deeper region of the internal granular layer. By the end of the first week (P8) UBCs were seen to invade the white matter + internal granular layer of lobules IX, VIII, I, and II of the vermis, and they spread further in the transitory area medio-laterally from the vermis toward the cerebellar hemispheres. By P15, UBCs appeared in lobules III and VII of the vermis, as well as in corresponding lobules of the neocerebellum, with especially high numbers in lobule VII. By P22, UBCs migrated further after their medio-lateral course in the neocerebellum, and began to invade lobules V and VI. At P62 the amount of UBCs in midsagittal planes of early developing vermal lobules (I, II, VII-X) resembled the P132 or adult pattern. The medio-lateral migration and incorporation of UBCs into the late-developing cerebellar lobules V and VI was completed only by P132, when the spatial distribution of UBCs in both the vermal and neocerebellar lobules was comparable to that seen in the 1 year old young adult cat. Although by P132 the postnatal migration of the vast majority of UBCs seemed to be completed, in the cerebellum of adult cats a few migrating UBCs could still be observed in the white matter of the cerebellar lobules, and beneath the ependyma of the fourth ventricle. It is concluded that during ontogenesis the migration course of UBCs follows essentially the developmental sequence of cerebellar lobules, although the incorporation of UBCs into the internal granular layer continues until 4 months postnatally, i.e., much beyond the apparent completion (about two months postnatally) of cytoarchitectonic built up of the cerebellar cortex of kittens.

Animals↗
PubMed1983

Stimulatory effect of beta-estradiol treatment on GABA-degradative enzymes within rat cerebellar cortex.

The influence of neonatal beta-estradiol treatment on the development of GABA-degradative enzymes (GABA transaminase and succinic semialdehyde dehydrogenase) within rat cerebellar cortex has been studied using a semiquantitative histochemical technique. Both enzymatic activities were stimulated following beta-estradiol treatment. In particular, the granule and Purkinje cells were the most influenced cerebellar components. The findings seem to suggest that granule and Purkinje cells may represent the principal target of the cerebellar cortex for sex hormones.

4-Aminobutyrate Transaminase↗
PubMed1992

Development of glutamic acid decarboxylase-immunoreactive elements in the cerebellar cortex of normal and lurcher mutant mice.

The development of glutamic acid decarboxylase-immunoreactivity (GAD-IR) in cells, fibers, and varicosities of the cerebellar cortex has been examined by light microscopy in normal and lurcher mutant mice between postnatal day 3 and 30 (P3-P30). Purkinje cell morphology was demonstrated in adjacent sections by using an antiserum to the 28Kd vitamin D-dependent calcium binding protein (CaBP). In early postnatal lurcher mice, but not in normal littermates, GAD-IR fibers, presumably Purkinje cell pseudopodia, invade the external granular layer. The plexus of CaBP-IR axons in the internal granular layer is much less complex in lurcher mice than in normal littermates, even before the onset of lurcher Purkinje cell degeneration at P8. In normal mice, GAD-IR fibers encapsulate Purkinje cell somata by P15. Lurcher Purkinje cells, in contrast, receive scattered contacts by GAD-IR puncta and possess a "cap" of such elements surrounding the primary dendrite and apical soma. Pinceau formations, visible as a knot of GAD-IR puncta hanging from the base of Purkinje cells in normal P15 mice, are not present in lurcher littermates. "Empty baskets" or collapsed pinceau formations in regions devoid of Purkinje cells are not revealed by anti-GAD immunohistochemistry in the P17-P30 lurcher cerebellar cortex.

Animals↗
PubMed1993

Expression of neuronal and glial polypeptides during histogenesis of the human cerebellar cortex including observations on the dentate nucleus.

In order to gain a more complete understanding of the sequential pattern of gene expression during neurogenesis and gliogenesis in humans, we followed the expression of well-characterized, developmentally regulated polypeptides in the cerebellar cortex and dentate nucleus by immunohistochemistry using monoclonal antibodies of highly defined specificity. At 8-10 weeks gestational age (GA), progenitor cells and their immediate progeny in the rhombencephalic ventricular zone expressed vimentin and nestin and, to a lesser extent, microtubule-associated protein 5 (MAP5) and glial fibrillary acidic protein (GFAP), but not the low affinity nerve growth factor receptor (NGFR). In contrast, postmitotic, migrating immature neurons in the intermediate zone gave strong reactions for MAP2, tau, and a nonphosphorylated form of middle molecular weight neurofilament (NF) protein (NF-M) and weak reactivity for NGFR. At 15 weeks GA, proliferating cells of the superficial part of the cerebellar external granular layer stained only for NGFR, while more deeply situated cells of the external granular layer stained positively for NGFR, MAP2, MAP5, tau, and chromogranin A, which correlates with the early outgrowth of parallel fibers. All phosphoisoforms of NF-M as well as the low (NF-L) and high (NF-H) molecular weight NF proteins and alpha-internexin were expressed in the somatodendritic domain of Purkinje cells and dentate nucleus neurons from about 20 weeks GA with a gradual compartmentalization of highly phosphorylated forms of NF-M and NF-H into axons by the end of gestation. Alpha-internexin was also expressed strongly in axons of the deep white matter from 20 weeks GA to adulthood. MAP2, synaptophysin, and NGFR showed early, transient expression in the somatodendritic domain of Purkinje cells followed by the appearance of a 220 kDa nestin-like peptide that continued to be expressed in adult Purkinje cells. Notably, developing dentate nucleus neurons expressed many of these proteins in a similar temporal sequence. Early in the developing cerebellar cortex, the expression of NF protein and synaptophysin occurred in discrete patches or columns similar to those described for other antigens (i.e., zebrins). Finally, radial glia were positive for vimentin, GFAP, and nestin from 8 weeks GA to 8 months postnatal. This study describes the distinct molecular programs of lineage commitment in cerebellar progenitor cells and in differentiating neurons and astrocytes of the human cerebellum. The acquisition of a mature molecular neuronal phenotype correlates with the establishment of structural polarity in cerebellar neurons.

Aging↗
PubMed1977

[Influence of destruction of the lateral reticular nucleus and nuclei of the inferior olive in cats on electrical responses of the cerebellar cortex evoked by stimulation of the vagus nerve].

The role of the lateral reticular nucleus and inferior olive in production of the cerebellar cortex evoked potentials to stimulation of n. vagus was studied on 28 cats under chloralose-nembutal narcosis. After electrolytical destruction of the lateral reticular nucleus prolongation of the latency and a decrease in the evoked potential amplitude were observed, especially ipsilaterally. After bilateral destruction the potentials could be depressed completely. A conclusion is made that the lateral reticular nucleus provides a relay to to the cerebellar cortex of interoceptive vagal impulses. Appearance of predominantly simple discharges of the Purkinje cells responses to vagal stimulation is considered as an additional evidence for such a role of the lateral reticular nucleus. After damaging the inferior olive the evoked potentials arose with unchanged latency but reduced in the amplitude. Significance of the inferior olive as an intensity regulatory for the interoceptive impulse flow to the cerebellum is discussed.

Animals↗
PubMed1984

Discrete lesions of the cerebellar cortex abolish the classically conditioned nictitating membrane response of the rabbit.

The classically conditioned nictitating membrane response (NMR) of the rabbit is useful for analyses of brain structures and pathways involved in mammalian associative learning. Lesions of the entire cerebellum, its nuclei or its efferent pathway abolish conditioned NMR learning and prevent its reacquisition. Until now it has not been clear whether the cerebellar cortex is an essential part of the circuitry for NMR conditioning. Here we report that small lesions of the cerebellar cortex in the hemispheral portion of lobule VI, with sparing of the underlying nuclei, abolish the ipsilateral conditioned NMR and prevent it from being reacquired.

Animals↗
PubMed1989

Somatostatin expression in the cerebellar cortex during postnatal development. An immunohistochemical study in the rat.

The distribution of somatostatin-immunoreactive (SOM-IR) elements in the cerebellar cortex of the rat has been studied at different stages of postnatal development (from birth to day 30) and in adult animals using immunohistochemistry. The results showed that in vermis of new born animals there are three main groups of SOM-IR structures within the cortex which subsequently spread along the Purkinje cell layer. In addition, both in the vermis and in the lateral lobes, numerous more evenly distributed SOM-positive cells and fibers could be seen. SOM-IR Golgi cells, Purkinje cells and climbing fibers could then be recognized during the subsequent developmental stages. In the vermal zone, SOM-IR Purkinje cells formed patches, which seemed to be part of a sagittal columnar or band-like organization. This was most obvious between days 5 and 21 of postnatal development. Subsequently there was a reduction in the number of immunoreactive Purkinje cells but a patchy disposition remained. In addition high numbers of SOM-IR Purkinje and Golgi cells and also climbing fibers were identified in the flocculus and paraflocculus at all stages of development studied, and they were also seen in the adult rats in these regions. In the lateral lobes expression of SOM-like immunoreactivity (LI) decreased and almost completely disappeared in adult animals. The present results demonstrate that a SOM or a SOM-LI peptide can be transiently detected in many Purkinje and Golgi cells in the cerebellar cortex, suggesting a role in events related to developmental processes. However, in some regions and structures SOM-LI can be seen also in adult animals.

Animals↗
PubMed1982

Regional organization of astrocytic membranes in cerebellar cortex.

The internal organization of plasmalemmal membrane, as revealed by freeze-fracture techniques, varies dramatically and predictably over the surface of astrocytes in mouse cerebellar cortex. Assemblies of uniform, small intramembrane particles packed in orthogonal order into square or rectangular aggregates are specialized distribution of intramembrane particles which, in the cerebellar cortex, are found only in astrocytes. The concentration of assemblies is greatest in astrocytic membrane juxtaposed to vascular structures or facing the cerebrospinal fluid at the glial limitans. Many fewer are present in regions of astrocytic membrane apposed to neural structures and virtually none are present on the astrocyte cell body. Corresponding structures have not yet been found in thin-sectioned preparations. While the distribution of assemblies in membranes facing blood and cerebrospinal fluid compartments suggests that they may have a role in transport of some material into or out of those compartments, their function is unknown. A second, distinct specialization of intramembrane structure appears to represent a junction between apposed astrocytic processes. We have provisionally described this as a 'polygonal particle junction', since it appears as large, irregular particles densely packed without obvious order in co-extensive regions of two astrocytic membranes. This junction is regularly present just below the cerebellar surface in the processes of the glial limitans as well as between large, more proximal radial Bergmann fibers, and also occurs occasionally throughout the molecular layer. With tannic acid mordant after aldehyde-osmium fixation or rapid freezing and freeze-substitution, it is possible to demonstrate subtle electron-dense specializations of the astrocytic membranes and extracellular matrix in thin-sections which correspond to the sites of polygonal particle junctions. The function of this astrocytic specialization is also unknown. Cerebellar astrocytes manifest numerous gap junctions as well, whose structure in freeze-fractured and thin-sectioned preparations is quite distinct from that of assemblies or of polygonal particle junctions.

Animals↗
PubMed1989

Thiamine-like molecules in the cerebellar cortex of the rat: light and electron microscopic immunocytochemical investigation.

Immunocytochemical methods were used for studying the location of thiamine-like molecules in the cerebellar cortex of the rat. A positive reaction was observed in several synapses and in several dendrites. This reaction was associated with tubular formations and synaptic vesicles. A positive reaction was also found in several mitochondria and in glial cells. The possible role of thiamine-like molecules in cerebellar cortex is discussed.

Animals↗
PubMed1986

Monoaminergic nerve terminals in the cerebellar cortex of Purkinje cell degeneration mutant mice: fine structural integrity and modification of cellular environs following loss of Purkinje and granule cells.

The cerebellar cortex of normal and Purkinje cell degeneration mutant mice was examined by electron microscopy after fixation with potassium permanganate for the demonstration of small granular vesicles in monoaminergic nerve terminals. In control mice, monoaminergic terminals were found mainly in apposition to Purkinje cell dendrites. After the degeneration of Purkinje cells, which constitute the major target for monoaminergic fibres in the cerebellum, monoaminergic terminals persisted in the cerebellar cortex of Purkinje cell degeneration mutant mice. They were ensheathed by astroglial processes in most of the instances. They were also apposed to boutons that contained agranular vesicles, and to stellate cells in the molecular layer. Clear synaptic specializations in the form of thickening of the synaptic membranes were not observed in either control or mutant mice. It is hypothesized that the survival of monoaminergic axons following loss of their target cells may be attributed to the lack of intimate adhesion to their target elements, to a possible functional interaction with the glia, or to the integrity of the extracerebellar terminal fields of the monoamine axon collaterals.

Adrenergic Fibers↗
PubMed1985

[Changes in the cerebellar cortex of rabbits subjected to an electrical current on the posterior hypothalamus].

After 3, 15 and 30 sessions of electrical stimulation of the hypothalamus by means of stereotaxically implanted bipolar electrodes into the area hypothalamica posterior, in the cortex of the cerebellar hemispheres, predominantly in the ganglionic layer, certain reactive, as well as poorly and intensively manifested pathological changes develop in neural and glial cells. Mosaicism of Purkinje's cells lesions within the layer, the state of their cytoplasmic matrix, granular endoplasmic reticulum and mitochondria, essential shifts in activity of oxidation-reduction enzymes at a simultaneous disorder in blood circulation and decreased content of catecholamines in the neural structures of the cerebellar vessels make it possible to estimate the process as centrogenic and neurodistrophic.

Animals↗
PubMed1999

Projection patterns of single mossy fibers originating from the lateral reticular nucleus in the rat cerebellar cortex and nuclei.

Projection of neurons in the lateral reticular nucleus (LRN) to the cerebellar cortex (Cx) and the deep cerebellar nuclei (DCN) was studied in the rat by using the anterograde tracer biotinylated dextran amine (BDA). After injection of BDA into the LRN, labeled terminals were seen bilaterally in most cases in the vermis, intermediate zone, and hemisphere of the anterior lobe, and in various areas in the posterior lobe, except the flocculus, paraflocculus, and nodulus. Areas of dense terminal projection were often organized in multiple longitudinal zones. The entire axonal trajectory of single axons of labeled LRN neurons was reconstructed from serial sections. Stem axons entered the cerebellum through the inferior cerebellar peduncle (mostly ipsilateral), and ran transversely in the deep cerebellar white matter. They often entered the contralateral side across the midline. Along the way, primary collaterals were successively given off from the transversely running stem axons at almost right angles to the Cx and DCN, and individual primary collaterals had longitudinal arborizations that terminated as mossy fibers in multiple lobules of the Cx. These collaterals arising from single LRN axons terminated bilaterally or unilaterally in the vermis, intermediate area, and sometimes hemisphere, and in different cerebellar and vestibular nuclei simultaneously. The cortical terminals of single axons appeared to be distributed in multiple longitudinal zones that were arranged in a mediolateral direction. All of the LRN axons examined (n = 29) had axon collaterals to the DCN. All of the terminals observed in the DCN and vestibular nuclei belonged to axon collaterals of mossy fibers terminating in the Cx.

Animals↗
PubMed1990

Autoradiographic localization of inhibitory and excitatory amino acid neurotransmitter receptors in human normal and olivopontocerebellar atrophy cerebellar cortex.

We used standard techniques of receptor autoradiography to study the distribution of inhibitory and excitatory amino acid neurotransmitter receptors in human normal cerebellar cortex. Benzodiazepine (BDZ) receptor density was relatively high in both granule cell and molecular layers. GABAA receptor density was highest in granule cell layer with lower receptor density in molecular layer. There was a lower density of GABAB receptors than GABAA receptors in both molecular and granule cell layers with a relatively higher density of GABAB receptors in molecular layer than in granule cell layer. In granule cell layer, the density of the N-methyl-D-aspartate (NMDA) subtype of excitatory amino acid receptors was greatest whereas in molecular layer the quisqualate (QA) receptor subtype density was greatest. With [3H]N-(1-[2-thienyl]cyclohexyl)3-4-piperidine as a ligand, there was no specific binding to the phencyclidine receptor. Molecular layer was also characterized by relatively high density of a non-NMDA/non-QA displaceable glutamate binding site. We studied also the cerebellar cortex of 4 cases of olivopontocerebellar atrophy (OPCA), a syndrome in which Purkinje and granule cells degenerate. In these specimens, there was significant decrement of BDZ and GABAA receptors in both molecular and granule cell layers, with loss of GABAB receptors in molecular layer. NMDA receptors were depleted in granule cell layer while QA receptors and the non-NMDA/non-QA glutamate binding site were significantly depleted in molecular layer. Our normal human and OPCA data are largely consistent with animal data about the cellular localization of cerebellar cortical amino acid neurotransmitter receptors.

Autoradiography↗
PubMed1999

[The modular organization of the granular layer of the human cerebellar cortex in postnatal ontogeny].

Age changes of microstructure of granular layer of the cortex of human cerebellum superior lobe (the area of clivus, posterior lateral regions of right and left tetrangular lobules) were studied in annual intervals from birth up to 20 yrs using computer analysis of optic images. Enlargement of the area of profile fields of cell groups in apical and basal regions of cerebellar folia from birth up to 14-15 yrs and differences between hemispheres in clasterization of granular layer were demonstrated. The data on age changes of cellular aggregations obtained allowed to formulate a hypothesis on autonomic local sensory networks of human cerebellar cortex associated with granular layer of cerebellar cortex that are considered as structural elements of module organization of the latter.

Adolescent↗