Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Spatial Distribution--changes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1999

Effects of sampling design on the estimation of adult mosquito abundance.

During 1994-5, Culex tarsalis comprised 75% of the 902,643 adult female mosquitoes collected by 63 dry-ice-baited Centers for Disease Control (CDC)-style traps operated biweekly in a uniform sampling grid that covered the southern Coachella Valley, Riverside County, California. The ln(y + 1) transformation successfully controlled the variance and normalized the distribution of catch size among trap nights. When tested by analysis of variance, abundance varied significantly among months, years, and trap sites. Although the trap by months interaction was not significant, female distribution changed seasonally as larval habitats shifted from wetlands along the Salton Sea to agriculture to managed duck marshes. Conditional simulations utilized subsets of trap sites to compare sampling designs that required no (uniform, random, and transect designs) or prior (best-estimate and stratified random designs) knowledge of mosquito spatial distribution. All designs provided similar information on population seasonal trends, but a stratified random design provided the most accurate and precise simulation. A uniform trap grid that employed every 2nd trap site subsequently was adopted by the Coachella Valley Mosquito and Vector Control District to provide information on focal changes in abundance indicative of missed or newly created larval habitats or control failures.

Animals↗
PubMed1992

Biochemical organization of single motor units in two multi-tendoned muscles of the cat distal forelimb.

In anesthetized cats single motor units (MUs) of the extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) muscles were selectively activated by stimulation of cervical ventral root filaments. The distribution of force developed by single MUs at the four distal tendons of the EDC muscle and at three portions of the distal tendon of the ECU muscle was analysed. In general, single MUs of both muscles distributed force over all tendons in a unimodal pattern, with the maximal force levels generated at one specific tendon which was termed the best-tendon. Distributions of force were quantitatively described by a parameter representing the mean direction of force output (output-index) and a further one representing the dispersion of force over the distal tendons (divergence). Generally, these parameters and the best-tendon remained stable when a MU was stimulated at different frequencies, but varied from MU to MU. Despite the general stability of the force distribution, slight systematic changes were regularly found in EDC MUs, when they developed a higher amount of force due to a higher frequency of stimulation: the relative amount of force at the best-tendon increased; e.g. the MUs got more selective for the best-tendon. These changes were partly due to overcoming mechanical cross-coupling between neighbouring compartments of the EDC muscle. Such changes of force distribution were only found in a part of the ECU MUs; other ECU MUs did not change their force distribution at all or became less selective for the best-tendon. The phenomenon that MUs of multi-tendoned muscles distribute their force output to the distal tendons in specific patterns is probably due to mechanical partitioning of the parent muscles: the localization of spatial territories of MUs within different anatomical muscle compartments should correspond to the best-tendon. Complex mechanisms allowing passive transmission of force from limited territories along the transverse axis of both muscles must be assumed in order to explain why most MUs act on all tendons and why force distributions change with increasing stimulus frequency. In addition, specific relations between unit type and force distributions were found within both muscles. Fatigue-resistant EDC MUs have broader force distributions than fatigue-sensitive EDC MUs and slow ECU MUs were found to act predominantly on the most ulnar part of the distal tendon. These biomechanical properties of MUs are discussed as supporting the specific functions of the respective muscles.

Animals↗
PubMed1999

Presence and dynamic redistribution of type I inositol 1,4,5-trisphosphate receptors in human oocytes and embryos during in-vitro maturation, fertilization and early cleavage divisions.

We studied the presence and distribution of the intracellular calcium channel regulating type I inositol 1,4,5-trisphosphate receptors (IP3R) in human immature and mature oocytes, pronuclear zygotes and cleaved embryos using a specific antibody. Two approaches were used: (i) fluorescence immunocytochemistry using a confocal laser scanning microscope (CLSM) and (ii) Western blotting. With confocal microscopy, the receptors were found in the oocytes, fertilized zygotes as well as cleaved embryos at all stages studied. The pattern and distribution of the receptor staining in the oocytes changed gradually from a diffuse granular patchy one at the germinal vesicle (GV) stage to a reticular and predominantly peripheral one through the metaphase I and metaphase II (MII) stages. After fertilization, the distribution changed gradually to both, peripheral and central in the zygotes and early 2-4-cell embryos and predominantly perinuclear in the 6-8-cell embryos. Furthermore, an overall increase in the staining intensity was observed from GV to MII stage oocytes and from zygotes to 6-8-cell embryos. We also studied the spatial distribution of the receptor in detail by constructing three-dimensional images from the serial optical sections obtained on the CLSM. Peculiar peripheral aggregates of receptor clusters were noted in the MII stage oocytes, zygotes and some blastomeres from early cleaved embryos. Finally, Western blots performed on the extracts of 72 in-vitro matured oocytes and 50 spare cleavage stage embryos showed positive bands at approximately 260 kDa. These findings coincide with and thus possibly represent the dynamic changes occurring in the cellular Ca2+ release systems through oocyte maturation, fertilization and early embryogenesis. Thus, type I IP3R are likely to play a role during these stages of early development in the human.

Animals↗
PubMed2000

Difference spatial distribution function analysis of aqueous solutions. II. Hydration structures of dimethyl ether, 180 degrees ethyl methyl ether and 0 degree ethyl methyl ether solutions.

Monte Carlo simulations are systematically presented to demonstrate the influence of the hydrophobic group's steric bulk on hydration structure. We have simulated a dimethyl ether (DME), two conformations for ethyl methyl ether (0 degree EME and 180 degrees EME), and 0 degree ethanol solutions. Spatial distribution function (SDF), goo(x,y,z) and difference SDF (DSDF), delta goo(x,y,z), obtained from MC simulation in an infinitely dilute aqueous solution of ether show the three-dimensional probability of an atom-atom pair distribution between solute and solvent atoms. Based on the results of SDF in an infinitely dilute aqueous solution of ether, the distribution of hydration water molecules can be divided into hydrogen acceptor (HA) and hydrophobic hydration (HH), regions, and the spatial orientation of the hydrogen-bonded water in the HA region is found to form a triple-layer structure, as it does in alcohol solutions. From the results of an analysis of the DSDF delta goo(x,y,z) between the SDFs of EME and DME, it is apparent that the distribution changes of hydration water molecules in ether solutions are essentially similar to those in the alcohol solutions. Further, we show that the hydration water molecules are distributed mainly in the stable area in the binding energy's (BE) contour maps for each region.

Algorithms↗
PubMed2000

Distributional changes of purinergic receptor subtypes (P2X 1-7) in uterine epithelial cells during early pregnancy.

Expression of each of the purinergic receptor subtypes (P2X7) was studied by immunohistochemical localization in the apical, lateral and basal plasma membranes of rat uterine epithelial cells during early pregnancy to the time of implantation on Day 6. Labelling for each P2X subtype was seen in the apical, lateral and basal compartments on Days 1 and 3, except for P2X2 which was only observed in the basement membrane. The P2X5 signal was similar in temporal and spatial expression to the other subtypes, but with a greatly reduced intensity. At the time of implantation on Day 6, this pattern altered dramatically. Apical expression markedly increased for most subtypes while the lateral and basal signals were markedly reduced. The exceptions to this pattern were P2X2, which displayed both a strong basal and apical label, and P2X4 which became de-expressed in all areas. We propose that the changing spatial and temporal expression of the P2X receptors is a significant factor in the regulation of events during early pregnancy. They are expressed in the same location as remodelling. apoptosis, and protein activation events prior to implantation on Day 6. These observations suggest an up-regulation of calcium-mediated events, including cytoskeletal alterations, a decrease in luminal pH and transmembrane molecule activation.

Animals↗
PubMed1999

Irregular chiasm-C-roughest, a member of the immunoglobulin superfamily, affects sense organ spacing on the Drosophila antenna by influencing the positioning of founder cells on the disc ectoderm.

We describe a role for Irregular chiasmC-roughest (IrreC-rst), an immunoglobulin (Ig) superfamily member, in patterning sense organs on the Drosophila antenna. IrreC-rst protein is initially expressed homogeneously on apical profiles of ectodermal cells in regions of the antennal disc. During specification of founder cells (FCs), the intracellular protein distribution changes and becomes concentrated in regions where specific intercellular contacts presumably occur. Loss of function mutations as well as misexpression of irreC-rst results in an altered arrangement of FCs within the disc compared to wildtype. Sense organ development occurs normally, although spacing is affected. Unlike its role in interommatidial spacing, irreC-rst does not affect apoptosis during antennal development. We propose that IrreC-rst affects the spatial relationship between sensory and ectodermal cells during FC delamination.

Animals↗
PubMed2000

Place recognition monitored by location-driven operant responding during passive transport of the rat over a circular trajectory.

Spatial memory of animals is usually tested in navigation tasks that do not allow recognition and recall processes to be separated from the mechanisms of goal-directed locomotion. In the present study, place recognition was examined in rats (n = 7) confined in an operant chamber mounted on the periphery of a slowly rotating disk (diameter 1 m, angular velocity 9 degrees /s). The animals were passively transported over a circular trajectory and were rewarded for bar pressing when they passed across a 60 degrees -wide segment of the path. This segment was recognizable with reference to room landmarks visible from the operant box. Responding defined in the coordinate system of the room increased when the chamber entered the 60 degrees -wide approach zone, culminated at the entrance into the reward sector, was decreased inside it by eating the available reward, and rapidly declined to zero at the exit from this zone. When reward was discontinued, the skewed response distribution changed into a symmetric one with a maximum in the center of the reward sector. With advancing extinction, the response peak in the reward sector decreased in most rats proportionally to the overall decline of bar pressing. The rewarded and nonrewarded response patterns indicate that passively transported rats can recognize their position in the environment with an accuracy comparable to that of actively navigating animals and that location-driven operant responding can serve as a useful tool in the analysis of the underlying neural mechanisms.

Animals↗
PubMed1985

Applied potential tomography: possible clinical applications.

Applied potential tomography (APT) or electrical impedance imaging has received considerable attention during the past few years and some in vivo images have been produced. This paper reviews the current situation in terms of what in vivo results have been and are likely to be obtained in the near future. Both static and dynamic imaging are possible and these two areas are dealt with separately. Features of the existing in vivo imaging system are good tissue contrast, high-speed data collection, good sensitivity to resistivity changes, low spatial resolution, low cost and no known hazard. It is concluded that the most promising way forward to clinical application in the short term is to use dynamic as opposed to static imaging. An example of lung imaging is shown and the application to measuring regional ventilation and pulmonary oedema is discussed. Use of APT for the detection of intraventricular bleeding in neonates is discussed as is the proven ability to study gastric physiology by imaging resistivity distribution changes following the ingestion of conducting or insulating fluids. Other areas of possible application which are considered are blood flow measurement, cell counting, measurement of lean-fat ratios and the detection of soft tissue lesions.

Cell Count↗
PubMed1996

Differential temporal evolution of post-training changes in regional brain glucose metabolism induced by repeated spatial discrimination training in mice: visualization of the memory consolidation process?

The present study analyses the effects of the stage of learning on the spatial patterns and time-course of [14C]glucose uptake in BALB/c mice brain regions produced by spatial discrimination training in an eight-arm radial maze. Our particular approach was designed to follow, during the post-training period, the level of functional activity in individual brain areas which may underlie the memory consolidation process. Regional mapping of relative [14C]glucose uptake was assessed at three post-training time intervals (5 min, 1 and 3 h) after either the first (Day 1), the fourth (Day 4) or the last (Day 9) daily training session of the discrimination task and compared with sham-conditioned animals placed in the same experimental environment. The results indicated that numerous subcortical and cortical brain regions exhibit metabolic alterations following the acquisition of the spatial discrimination task. These alterations, which were specifically related to learning since they did not appear in sham-conditioned animals, were functions both of the post-training interval studied and of the degree of mastery of the task. On Day 1, a progressive, time-dependent and sequential increase in labelling was found from subcortical (5 min post-training) to cortical regions (3 h post-training). On Day 4, a peak of cortical metabolic activation was identified at 1 h post-training. In contrast, on Day 9, maximum labelling was found 5 min post-training in all subcortical and cortical regions followed by a general monotonic decline at 1 and 3 h post-training. These findings, which show widely distributed changes of metabolic activity in the brain, are consistent with the hypothesis that learning involves distributed neural networks. The sequential activation from subcortical to cortical regions seems to indicate a general mechanism whose function would ultimately be to store cortical memory representations. The acquisition-dependent shifts in the patterns of post-training metabolic labelling observed as a function of task mastery may be taken to represent a visualization of the spatio-temporal evolution of the networks of brain structures actively engaged in the memory consolidation process. In particular, the present data suggest that the duration of post-acquisition memory processing is a function of the quantity of new information which has to be dealt with by the central nervous system.

Animals↗
PubMed1993

GABAA and glutamate receptor involvement in dendrodendritic synaptic interactions from salamander olfactory bulb.

1. Whole-cell patch clamp and optical recording techniques were applied to the same in vitro salamander olfactory bulb preparations to study the postsynaptic responses of single mitral/tufted cells in the context of the surrounding neural activity in which they are embedded. Mitral/tufted cells were identified by intracellular filling with biocytin. 2. Single mitral/tufted cells were under a tonic GABAA receptor-mediated inhibitory influence as revealed by the recording of bicuculline methiodide (BMI)/picrotoxin-sensitive inhibitory postsynaptic currents (IPSCs) in symmetrical chloride conditions at a holding potential of -70 mV. Depolarizing voltage steps (100 ms) applied to single cells or electrical stimulation of the olfactory nerve or medial olfactory tract evoked a prolonged increase in the frequency of GABAergic IPSCs. 3. The frequency of spontaneous and driven IPSCs was reduced with application of the glutamate receptor antagonists 6-cyano-2,3-dihydroxy-7-nitro-quionoxaline (CNQX) or 2-amino-5-phosphonopentanoic acid (AP5) whereas olfactory nerve- or medial olfactory tract-driven IPSC frequency was enhanced with removal of bathing Mg2+, indicating that GABAergic interneurones were driven by mitral/tufted cells at both non-NMDA and NMDA receptors. 4. Olfactory nerve or medial olfactory tract stimulation evoked widely distributed changes in fluorescence in preparations stained with the voltage-sensitive dye RH414. The optical response predominantly consisted of a decrease in fluorescence, indicative of depolarization. The presence of the dye did not obviously affect mitral/tufted cell postsynaptic responses. 5. BMI enhanced the amplitude and duration of optical signals related to depolarization within the bulb and in regions central to the bulb. In the presence of BMI, depolarizing activity appeared to spread hundreds of micrometres into regions of the bulb not activated in control conditions showing explicitly that GABAA receptors in the bulb participate in lateral inhibition. 6. CNQX and AP5 attenuated the optical signals within the bulb supporting the contention that in these conditions, optical signals arise mainly from granule cell dendritic activity. Furthermore, AP5 or removal of bath Mg2+ reduced or enlarged the spatial distribution of activity respectively, suggesting that in some cases the NMDA receptor may be involved in generating or stabilizing spatial patterns of activity. 7. It is concluded that in the salamander olfactory bulb, both GABAA- and glutamate receptor-mediated synaptic transmission shape the different temporal and spatial patterns of neural activity associated with olfactory coding.

2-Amino-5-phosphonovalerate↗
PubMed1990

Global field power and topographic similarity.

Multichannel recordings are commonly presented as topographic maps series displaying the change of the potential distribution over time. When reviewing a sequence of potential maps it becomes obvious that there are epochs with only little activity (few field lines; small extrema values) while at other times the fields display high peaks and deep troughs with steep gradients. The measure of global field power (GFP) corresponds to the spatial standard deviation, and it quantifies the amount of activity at each time point in the field considering the data from all recording electrodes simultaneously resulting in a reference-independent descriptor of the potential field. Global field power is plotted as a function of time, and the occurrence times of GFP maxima are used to determine the latencies of evoked potential components. The topographical change occurring in subsequent potential field distributions may also be quantified by computing an index of global dissimilarity. Global field power and global dissimilarity show a complementary behavior over time: in general, high GFP is associated with similar fields while during periods between GFP peaks the topographic patterns of successive field distributions change rapidly accompanied by high dissimilarity values. The topographic changes, however, are best recognized by a segmentation procedure that considers field structure independent of GFP and global dissimilarity. The principles and practical applications of GFP computation, component latency determination and global dissimilarity of potential field distributions as well as a topographical time segmentation procedure will be illustrated with multichannel data evoked by visual stimuli.

Brain↗
PubMed1995

Observation of extremely heterogeneous electroporative molecular uptake by Saccharomyces cerevisiae which changes with electric field pulse amplitude.

Molecular uptake of a charged fluorescent molecule (calcein; 623 Da, z = -4) was quantitatively determined at the single cell level using flow cytometry. Dilutely suspended cells were exposed to one exponential pulse (tau p approximately 300 microseconds) for different field strength values. For an asymmetric cell such as the yeast Saccharomyces cerevisiae a significant variation in the number of molecules taken up by individual cells was expected for physical reasons. By carrying out several thousand individual cell measurements for each pulse condition, we found that the number of molecules per cell varies significantly within the cell population, and that this population distribution changes markedly as the field strength is varied. Surprisingly, in spite of significant changes in this distribution with field strength, the average uptake per cell reaches a non-equilibrium plateau for which the uptake per cell is much smaller than the product of the mean cell volume and the supplied extracellular concentration. These observations of different field-dependent cell population distributions of uptake support the hypotheses that (1) electroporation is a transmembrane voltage-responsive phenomenon, so that cells of different sizes, shapes and orientation, respond differently to even a spatially uniform applied field, (2) population average measurements of electroporation behavior can be incomplete and misleading, and (3) transport of small charged molecules is due to electrophoresis through the pores of a dynamically changing pore population.

Cell Membrane↗
PubMed1992

New method of estimating the ultrasonic beam ratio parameter for characterizing sound propagation in tissue.

The backscattered ultrasonic signal from soft tissue can be considered to consist of two parts: a spatially fluctuating component due to coherent scattering from randomly distributed scattering centers and a relatively constant component related to structural ordering. The relationship between these, which has been termed the "beam ratio parameter" influences the speckle pattern of an ultrasound image. First-order image statistics for this special speckle pattern are characterized by the Rician distribution. Changes of second-order statistics have also been derived as a function of the beam ratio parameter. A new method for the estimation of the beam ratio parameter from the intensity distribution of the ultrasonic signal is described in this paper. This method was used to measure the parameter in ultrasonic images from phantoms and liver tissue yielding values of about 0.1. The measured changes of the second-order statistics were not correlated to this parameter. The results indicate that the relatively constant intensity component related to structural ordering has only a small influence on the speckle pattern.

Biopsy↗
PubMed1994

Rate and pattern of migration of lineally-related olfactory bulb interneurons generated postnatally in the subventricular zone of the rat.

A spatially discrete region of the anterior part of the postnatal telencephalic subventricular zone, referred to as the SVZa generates vast numbers of lineally-related neurons destined for the olfactory bulb (Luskin, 1993). The cells originating in the SVZa migrate to the olfactory bulb along a highly restricted pathway which is in a direction orthogonal to the orientation of radial glial fibers. In this study we analysed the number, distribution, orientation and rate of migration of SVZa-derived cells as they approach the olfactory bulb. In order to track the SVZa-derived cells, a retroviral lineage tracer, encoding the reporter gene E. coli beta-galactosidase (lacZ) was injected precisely into the rat SVZa at postnatal day 1 (P1). The lacZ-positive cells were visualized 1, 2 and 3 days later by X-Gal histochemistry in cryostat sections. As the number of SVZa-derived cells in the pathway increased with survival time, their distribution changed systematically. The distribution pattern of lacZ-positive cells by 2 and 3 days postinjection suggested that some of the progeny of infected progenitor cells were undergoing neurogenesis as they proceeded to the olfactory bulb; a large percentage of the lacZ-positive cells were substantially displaced from the SVZa injection site. To investigate whether lacZ-positive cells migrate in a directed fashion, their orientation preference was scored. For the majority of lacZ-positive cells (> 94%), their leading process was directed toward the olfactory bulb, possibly reflecting a response to migratory cues present along the pathway. The estimated average rate of cell migration to the olfactory bulb was 23 mu m/h, which is approximately twice the speed of radially directed neuronal migration from the telencephalic ventricular zone to the cortical plate (O'Rourke et al., 1992). Collectively, these results suggest that SVZa-derived interneurons en route to the olfactory bulb may employ a novel mode of tangential migration.

Animals↗
PubMed1991

Seasonality of peridomestic cockroaches (Blattoidea: Blattidae): mobility, winter reduction, and effect of traps and baits.

Populations of smokybrown cockroaches, Periplaneta fuliginosa (Serville), and Eurycotis floridana (Walker) were studied to compare mobility and population size between fall 1985 and spring 1986 seasons at site A, and to assess the effect of a combination of traps and baits at site B in northcentral Florida. Adult smokybrown cockroaches were more mobile in the spring than in the fall; a similar trend for E. floridana adults was not significant. Overall population levels were reduced after winter by approximately 73%. No significant shift in spatial distributions of nymphs occurred, but adult distribution changed from a predominance in palms (fall) to hardwood trees with tree holes (spring), suggesting that this habitat offers better survival during winter. Removal of cockroaches by trapping at site B, followed by a single application of dry distiller's grain containing 0.5 chlorpyrifos, reduced expected population levels (based on site A data) by 90% measured at 6 mo after treatment. These data refute the hypothesis that an increase in numbers of cockroaches infesting homes in the fall is due to an increase in mobility. Instead, the results suggest that population size and proximity of principal habitats to the home are probably responsible for domestic infestations in the fall. Use of traps, baits, or both at these foci significantly reduce populations over an extended period.

Animals↗
PubMed1988

Assessment of lung water distribution by nuclear magnetic resonance. A new method for quantifying and monitoring experimental lung injury.

We have developed a new analytical method that uses nuclear magnetic resonance (NMR) imaging data to quantify lung water content and distribution. This new method generates a distribution of lung water density in which the fraction of voxels corresponding to a given water density is plotted on the vertical axis as a function of water density on the horizontal axis, thereby complementing the spatial information provided by the NMR image. We obtained reproducible lung water distribution data at comparable lung volumes in normal excised lungs and in intact living rats. In normal excised unperfused rat lungs, the distribution varied with the degree of inflation, but the changes were small compared with those associated with lung edema. The lung water density distribution changed markedly after induction of lung edema by intrabronchial saline instillation, intravenous oleic acid injection, and rapid intravenous saline infusion. Lung water density distribution data were well correlated (correlation coefficient = 0.948 for the excised lungs and 0.823 for the intact living rats) with gravimetric lung water measurements. The new analytical method is noninvasive, provides easily repeatable measurements, and is as sensitive as the gravimetric technique to lung water changes.

Animals↗
PubMed1999

Regulated expression and subcellular localization of syndecan heparan sulfate proteoglycans and the syndecan-binding protein CASK/LIN-2 during rat brain development.

The syndecan family of cell surface heparan sulfate proteoglycans interacts via their cytoplasmic C-terminal tail with the PDZ domain of CASK/LIN-2, a membrane-associated guanylate kinase homolog. The syndecan-CASK interaction may be involved in intercellular signaling and/or cell adhesion. Here we show that syndecan-1 to syndecan-4 have distinctive mRNA distributions in adult rat brain by in situ hybridization, with syndecan-2 and -3 being the major syndecans expressed in neurons of the forebrain. At the protein level, syndecan-2 and -3 are differentially localized within neurons; syndecan-3 is concentrated in axons, whereas syndecan-2 is localized in synapses. The synaptic accumulation of syndecan-2 occurs late in synapse development. CASK is a cytoplasmic-binding partner for syndecans, and its subcellular distribution changes strikingly during development, shifting from a primarily axonal distribution in the first 2 postnatal weeks to a somatodendritic distribution in adult brain. This change in CASK distribution correlates temporally and spatially with the expression patterns of syndecan-3 and -2, consistent with the association of both of these syndecans with CASK in vivo. In support of this, we were able to coimmunoprecipitate a complex of CASK and syndecan-3 from brain extracts. Our results indicate that specific syndecans are differentially expressed in various cell types of the brain and are targeted to distinct subcellular compartments in neurons, where they may serve specialized functions. Moreover, CASK is appropriately expressed and localized to interact with both syndecan-2 and -3 in different compartments of the neuron throughout postnatal development.

Aging↗
PubMed1991

Changes in the distribution of extracellular matrix components accompany early morphogenetic events of mammalian cortical development.

As a step in defining the molecular environment for development of the mammalian cerebral cortex, we have used immunohistochemistry to analyze the distribution and remodeling of three major extracellular matrix (ECM) components, fibronectin, chondroitin sulfate proteoglycan (CSPG), and tenascin, during embryonic and early postnatal stages in the mouse. Fibronectin and CSPG are distributed throughout the proliferative zone that initially comprises the thin wall of the telencephalic vesicle, but their distribution changes as newly generated cells form the preplate just beneath the pia. Immunolabeling for CSPG becomes most prominent in the preplate, and fibronectin becomes restricted to that layer. Just after this change occurs, processes of preplate neurons, visualized with antibodies to neurofilaments, become evident within the matrix-rich preplate zone. The association of fibronectin and CSPG with preplate cells persists as cortical plate neurons divide the preplate; both ECM components are now most prominent in the marginal zone and subplate, the layers above and below the cortical plate that are preplate derived. Within the preplate and its derivatives, immunolabeling of fibronectin is punctate and closely associated with radial glial processes, while labeling of CSPG is more intense and diffuse. Labeling of fibronectin and CSPG declines rapidly as the cortical plate begins to differentiate into cortex; labeling for tenascin first appears at this stage in the most mature layers, the marginal zone and subplate, then gradually becomes widespread throughout all of cortex and subcortical white matter. In early postnatal life, tenascin is eliminated from the hollows of the vibrissal barrels in the somatosensory region; it then declines rapidly throughout cortex. The association of both fibronectin and CSPG with preplate cells and the distribution of fibronectin along radial glia during early cortical development suggest that one or both of these transient cell types might produce specific ECM components or induce their local deposition. The spatial and temporal distribution of fibronectin and CSPG suggests a role in defining a destination for migrating neurons that form the cortical plate and in delineating the pathway for early axonal extension. In contrast, the relatively late appearance of tenascin correlates best with the formation of astrocytes and their processes rather than with the establishment of cortical layers or major axonal pathways. These events are well underway before labeling of tenascin is evident.

Animals↗