Cortical Cell Morphology Research Articles

Assessment of Zebrafish Lens Nucleus Localization and Sutural Integrity.

The zebrafish is uniquely suited to genetic manipulation and in vivo imaging, making it an increasingly popular model for reverse genetic studies and for generation of transgenics for in vivo imaging. These unique capabilities make the zebrafish an ideal platform to study ocular lens development and physiology. Our recent findings that an Aquaporin-0, Aqp0a, is required for stability of the anterior lens suture, as well as for the shift of the lens nucleus to the lens center with age led us to develop tools especially suited to analyzing the properties of zebrafish lenses. Here we outline detailed methods for lens dissection that can be applied to both larval and adult lenses, to prepare them for histological analysis, immunohistochemistry and imaging. We focus on analysis of lens suture integrity and cortical cell morphology and compare data generated from dissected lenses with data obtained from in vivo imaging of lens morphology made possible by a novel transgenic zebrafish line with a genetically encoded fluorescent marker. Analysis of dissected lenses perpendicular to their optical axis allows quantification of the relative position of the lens nucleus along the anterior-posterior axis. Movement of the lens nucleus from an initial anterior position to the center is required for normal lens optics in adult zebrafish. Thus, a quantitative measure of lens nuclear position directly correlates with its optical properties.

Cuticle and cortical cell morphology of alpaca and other rare animal fibres

The null hypothesis of the experiments reported is that the cuticle and cortical morphology of rare animal fibres are similar. The investigation also examined if the productivity and age of alpacas were associated with cuticle morphology and if seasonal nutritional conditions were related to cuticle scale frequency. Cuticle and cortical cell dimensions and ellipticity of the fibre cross section were investigated in 32 samples of cashmere, alpaca, mohair, bison, qiviut and vicuña from various origins. In addition, 24 Peruvian alpaca samples from animals ages 2–6 years and of varying fleece productivity were examined. Cuticle scale frequency, cuticle thickness and cortical cell dimensions (length, diameter, volume and ratio of length to diameter) and ellipticity differed between fibres and cuticle scale frequency also varied with mean fibre diameter. For Peruvian alpaca fleece samples, cuticle scale frequency varied with the age of alpaca and fleece productivity. Fibre ellipticity increased with increasing fibre diameter. Cortical cell length was strongly related to cortical cell diameter. The cuticle scale morphology of these rare animal fibres did not have fixed dimensions. Using cuticle scale morphology as a diagnostic tool to positively identify rare natural animal fibres needs to standardize measurements for fibre diameter but will still be affected by differences in animal productivity.

Cuticle and cortical cell morphology and the ellipticity of cashmere are affected by nutrition of goats

Cuticle scale edge height and frequency are used to identify animal fibres but exhibit a large range in dimensions, the reasons for which have not been elucidated. Cuticle and cortical cell dimensions along with the ellipticity of fibres were investigated in cashmere samples from a controlled nutrition experiment. Cuticle scale frequency, cuticle thickness, cortical cell dimensions and ellipticity were affected by nutritional treatment, with significant differences between cashmere from goats fed to grow and those which maintained live weight or lost weight. Cuticle scale frequency, cell thickness and ellipticity (contour) varied with fibre diameter, fibre growth rate and the size of the animals. Cuticle thickness and ellipticity were related. Cashmere grown by goats with higher levels of nutrition had longer cortical cells with greater diameter, volume and a higher length:diameter ratio compared with cashmere grown by goats in restricted nutrition treatments. The results show that the fundamental physical structures of cashmere do not have fixed dimensions. The consequences of the variations in cuticle morphology and ellipticity will be variation in surface friction, bending rigidity, softness, lustre, colour attributes, fibre cohesion during processing, felting and wear properties of textiles. There are also important consequences upon the determination of cashmere origin.

Deletion of the citron kinase gene selectively affects the number and distribution of interneurons in barrelfield cortex

Citron kinase (CIT-K), a ser/thr kinase, is required during neurogenesis for cytokinesis of neuronal precursors. Deletion of the cit-k gene in mice (cit-k−/− mice) leads to a severe malformative central nervous system syndrome characterized by microencephaly, ataxia, and epileptic seizures; affected mice die by the third week of postnatal life. We have used NADPH-diaphorase histochemistry, immunostaining for calbindin, calretinin, parvalbumin, and glutamic acid decarboxylase 67 (GAD67), and histological staining to undertake qualitative and quantitative analyses of the morphology and distribution of interneurons in the barrelfield cortex of cit-k−/− mice. By postnatal day 13, lack of CIT-K results in profoundly altered cortical cell morphology: the infragranular layers are populated by large, binucleate interneurons bearing many more dendrites than in control mice, an anatomical profile that has also been reported for the cortex of humans with cortical dysplasias and epilepsy. Tessellation analyses reveal that a clustered distribution of interneurons is maintained in cit-k−/− mice, but that their nearest neighbor distance is significantly increased, and thus their density is reduced; the overall number of interneurons is more dramatically decreased in the absence of CIT-K than would be predicted on the basis of the reduced brain size of affected mice. This reduction of inhibitory γ-aminobutyric acid (GABA)ergic neurons likely underlies the occurrence of epileptic seizures in the cit-k−/− mice. Furthermore, the altered distribution of NADPH-diaphorase-positive interneurons could be responsible for an impaired coupling of cortical activity to blood flow, also affecting cortical growth and functioning. J. Comp. Neurol. 513:249–264, 2009. © 2009 Wiley-Liss, Inc.

Deletion of the citron kinase gene selectively affects the number and distribution of interneurons in barrelfield cortex

AbstractCitron kinase (CIT‐K), a ser/thr kinase, is required during neurogenesis for cytokinesis of neuronal precursors. Deletion of the cit‐k gene in mice (cit‐k−/− mice) leads to a severe malformative central nervous system syndrome characterized by microencephaly, ataxia, and epileptic seizures; affected mice die by the third week of postnatal life. We have used NADPH‐diaphorase histochemistry, immunostaining for calbindin, calretinin, parvalbumin, and glutamic acid decarboxylase 67 (GAD67), and histological staining to undertake qualitative and quantitative analyses of the morphology and distribution of interneurons in the barrelfield cortex of cit‐k−/− mice. By postnatal day 13, lack of CIT‐K results in profoundly altered cortical cell morphology: the infragranular layers are populated by large, binucleate interneurons bearing many more dendrites than in control mice, an anatomical profile that has also been reported for the cortex of humans with cortical dysplasias and epilepsy. Tessellation analyses reveal that a clustered distribution of interneurons is maintained in cit‐k−/− mice, but that their nearest neighbor distance is significantly increased, and thus their density is reduced; the overall number of interneurons is more dramatically decreased in the absence of CIT‐K than would be predicted on the basis of the reduced brain size of affected mice. This reduction of inhibitory γ‐aminobutyric acid (GABA)ergic neurons likely underlies the occurrence of epileptic seizures in the cit‐k−/− mice. Furthermore, the altered distribution of NADPH‐diaphorase‐positive interneurons could be responsible for an impaired coupling of cortical activity to blood flow, also affecting cortical growth and functioning. J. Comp. Neurol. 513:249–264, 2009. © 2009 Wiley‐Liss, Inc.

Deletion of the citron kinase gene selectively affects the number and distribution of interneurons in barrelfield cortex

Citron kinase (CIT-K), a ser/thr kinase, is required during neurogenesis for cytokinesis of neuronal precursors. Deletion of the cit-k gene in mice (cit-k(-/-) mice) leads to a severe malformative central nervous system syndrome characterized by microencephaly, ataxia, and epileptic seizures; affected mice die by the third week of postnatal life. We have used NADPH-diaphorase histochemistry, immunostaining for calbindin, calretinin, parvalbumin, and glutamic acid decarboxylase 67 (GAD67), and histological staining to undertake qualitative and quantitative analyses of the morphology and distribution of interneurons in the barrelfield cortex of cit-k(-/-) mice. By postnatal day 13, lack of CIT-K results in profoundly altered cortical cell morphology: the infragranular layers are populated by large, binucleate interneurons bearing many more dendrites than in control mice, an anatomical profile that has also been reported for the cortex of humans with cortical dysplasias and epilepsy. Tessellation analyses reveal that a clustered distribution of interneurons is maintained in cit-k(-/-) mice, but that their nearest neighbor distance is significantly increased, and thus their density is reduced; the overall number of interneurons is more dramatically decreased in the absence of CIT-K than would be predicted on the basis of the reduced brain size of affected mice. This reduction of inhibitory gamma-aminobutyric acid (GABA)ergic neurons likely underlies the occurrence of epileptic seizures in the cit-k(-/-) mice. Furthermore, the altered distribution of NADPH-diaphorase-positive interneurons could be responsible for an impaired coupling of cortical activity to blood flow, also affecting cortical growth and functioning.

Thermoanalytical characterisation of modified keratin fibres

In the wool textile industry, several processes serve to improve the commercial properties of the fibres such as fineness, softness, length, strength and lustrous. For example, wool is chemically treated with reductive agents then stretched and set. This leads to modifications of the original protein structure causing changes in thermal behaviour, dyeing, colouristic and wet resistance properties. A multidisciplinary approach was used to investigate treated and untreated wools, with the aim of exploiting the nature of the structural changes. SEM and TEM revealed changes on the cuticle and cortical cell morphology; structure modification were studied by FT-IR and DSC.

Seasonal Adreno-Cortical Cycle of a Nocturnal Bird, Indian Spotted Owlet Athene brama: Biochemical and Morphological Observations

It is well reported that the environmental factors along with different endocrine stimulus play a crucial role in maintenance of adrenocortical activity in birds. This study is first to report a detailed seasonal activity cycle of adrenal cortex, particu-larly its secretory physiology in a tropical nocturnal bird, Indian spotted owlet Athene brama. The maximum cortical activity having highest glandular mass, glandular free cholesterol, esterified cholesterol profiles, and peak level of corticosterone in plasma coincided with the long day length, highest temperature and increasing amplitude of relative humidity and rainfall of the early summer month, May. Cortical activity declined to minimum level in August when the ecofactors also declined parallely and hence, the birds entered into partial hibernation. The cortical activity progressed slowly throughout the winter (September–March) to reach maximum level in May. Further, the electron microscopic observations of cortical cell morphology strongly supported the above seasonal activity status of the gland revealing a comparatively large number of mitochondria during May than August, along with lipid filled vacuoles during May but not in August. Besides, assessment of gonadal and pineal hormones in relation with seasonal activity of adrenal cortex presented a parallel relationship with gonad while completely inverse relationship with pineal. Therefore, the study concludes that the seasonal adrenocortical activity of this tropical nocturnal bird might be regulated by multiple factors, particularly by the environmental temperature, humidity/rainfall and photoperiod along with the internal factors at least by gonadal and pineal hormones.

Dual channel confocal laser scanning microscopy of lucifer yellow-microinjected human brain cells combined with Texas red immunofluorescence

A method for visualization of individual human brain cells and their dendritic extensions in combination with immunofluorescence is described. Microinjection of Lucifer Yellow was used to reveal the dendritic morphology of cortical brain cells. Indirect immunofluorescence with Texas Red as label was used to investigate the distribution of 3 different groups of immunogens: enzymes (monoamine oxidase A and B), receptors (β-adrenoceptor protein), and synaptic vesicle proteins (synapsin I and synaptophysin) in each cortical slice. A dual-channel confocal laser scanning microscope with an argon/krypton laser was used for imaging these double-stained fluorescent specimens. Lucifer Yellow and Texas Red were recorded simultaneously or separately, taking advantage of the different activating lines (488 λ and 568 λ) of the laser and using the two filter blocks (K1 and K2) supplied with the instrument (BioRad MRC-600) for recording the emission of either fluorophore. Using this technique we have demonstrated the localization of immunoreactive material in relatation to the dendritic morphology of cortical cells.

Sphagnum aureum, a New Species from Costa Rica

Sphagnum aureum sp. nov. (section Sphagnum) is reported from high elevation peatlands in Costa Rica. This species is similar to S. alegrense and S. magellanicum, but differs from these species in branch leaf, stem leaf, and cortical cell morphology. While collecting bryophytes in Costa Rica, I found specimens of Sphagnum that represent a new species in section Sphagnum of the genus. SPHAGNUM AUREUM McQueen, sp. nov. (FIG. 1-8) Plantae pallido-auricolores, pallido-fuscae. Cellulae epidermidis caulinae stratis 3, fibrosae, parietibus exterioris cellularum superficialium foraminibus 1-2(-3) instructis, apice porosis ellipticis. Folia caulina plana, late lingulata, 1.0-1.4 mm longa; cellulae hyalinae breves, non septatae, non fibrosae, aporosae. Rami 4 in fasciculo. Folia ramulina 1.0-1.5 mm longa, ovata, concava; cellulae hyalinae dorso poris magnis in clelularum angulis, interiore folii superficie aporosae; cellulae chlorophylliferae sectione transversali ellipticae, intercellulas hyalinas perfecte mediae, utrinque inclusae. Plants pale gold, tan, or light-brown. Stem cortical cells in 3 layers, fibrillose, outer cortical cells with 1-2 (sometimes 3) pores, apical pore commonly elliptical. Stem leaves flat, lingulate, 1.0-1.4 mm long; hyaline cells short, undivided, without pores or fibrils. Branches in fascicles of 4 (2 spreading, 2 pendent). Branch leaves 1.0-1.5 mm long, oblong-ovate, deeply concave; hyaline cells of outer surface with pores in groups of 3 at adjacent angles and with a few singly at sides, inner surface aporose or with only a few pores; chlorophyllous cells elliptic in cross section, central, entirely included, hyaline cells slightly convex on both surfaces, with smooth inner walls. TYPE: COSTA RICA. In wet seep near lower limit of piramo of north face of Cerro de la Muerte, 3,250 m, Cyrus B. McQueen 4020 (holotype, vT; isotype, CR). This species resembles S. alegrense Warnst. and S. magellanicum Brid., but differs from both in a number of features (Fig. 1-8): S. aureum is pale gold, tan, or pale brown, without any red coloration as in S. magellanicum and S. alegrense. The chlorophyllose cells of the branch leaves are similar to those of S. magellanicum. Sphagnum aureum and S. magellanicum differ from S. alegrense, in that they lack the vermiform ridges on the inner side walls (Allen 1986; Crum 1980, 1984). Sphagnum aureum also has fibrillose cortical cells as in S. magellanicum, whereas those of S. alegrense are efibrillose. Some other unique features of S. aureum are that on the inner surface the branch leaf hyaline cells are aporose or have only a few pores. The stem leaves of anisophyllous plants are about half the length of those of S. magellanicum. The pores of the cortical cells are also different from those of S. magellanicum and S. alegrense in that there are 2 pores (rarely 3) per cell and the upper pore of each cell is elliptic in shape. The anisophyllous plants of S. aureum that I collected were growing at the lower limit of the pairamo of Cerro de la Muerte. The plants formed small, tightly compact hummocks at the bases of stands of bamboo and small cushions on the edges of eroded stream banks. The pH of standing water around the S. aureum populations ranged from 3.95 to 4.95 (based on seven samples). Sporophytes were found on some plants in each of the small hummocks and cushions that I found. Other species growing in the type locality include S. alegrense, S. magellanicum, S. meridense (Hampe) C. Miill., S. sparsum Hampe, and S. perichaetiale Hampe.

Pyramidal cortical cell morphology studied by multivariate analysis: effects of neonatal thyroidectomy, ageing and thyroxine-substitution therapy

The changes produced on the whole dendritic morphology of layer III cortical pyramidal neurons by neonatal hypothyroidism, induced in rats by thyroidectomy at 10 days of age (T), as well as those changes related to ageing, have been studied in rats at 40 and 80 days of age. For these purposes, the dendritic structure of these neurons was defined by a set of 10 variables whose measurements were analyzed using multivariate methods. The effect of tyroxine (T 4) substitution therapies applied to T rats between 12–40 and 30–80 days of age has been further investigated with the same mathematical methodology. The results obtained from the analyses performed show that hypothyroidism affects both the apical tuft and the basal dendritic arborization of these neurons. The observed damage was similar: a decrease of the total length of the dendritic segments of the apical tuft and the basal arborization. This change, however, was detected in these two different subregions with a different timing. These results seem to reinforce our findings concerning the selective effect of T on different sites of these neurons. On the other hand, 3 morphological changes have been revealed regarding the development of the pyramidal neuron studied: (1) the total length of the apical tuft dendritic segments increases from 40 to 80 days of age; (2) the total length of the basal dendritic segments decreases from 40 to 80 days of age; and (3) the perimeter of the cell body decreases from 40 to 80 days of age. Finally, the results obtained did not allow us to detect any recovery of the damage induced by T, as a consequence of the T 4 substitution therapies applied.

Stellar Atmospheres: The A-Stars . Problems and Perspectives. Sidney C. Wolff. Centre National de la Recherche Scientifique, Paris, and NASA Scientific and Technical Information Branch, Washington, D.C., 1983 (available from Stuart Jordan, Goddard Space Flight Center, Greenbelt, Md. 20771). xlvi, 211 pp., illus. Cloth. Monograph Series on Nonthermal Phenomena in Stellar Atmospheres. NASA SP-463.

Stellar Atmospheres: <i>The A-Stars</i> . Problems and Perspectives. Sidney C. Wolff. Centre National de la Recherche Scientifique, Paris, and NASA Scientific and Technical Information Branch, Washington, D.C., 1983 (available from Stuart Jordan, Goddard Space Flight Center, Greenbelt, Md. 20771). xlvi, 211 pp., illus. Cloth. Monograph Series on Nonthermal Phenomena in Stellar Atmospheres. NASA SP-463.

The distribution and morphology of opioid peptide immunoreactive neurons in the cerebral cortex of rats

Pharmacological and biochemical evidence has implied that a widespread opioid peptide system exists within the cerebral cortex to mediate a variety of opiate effects. However, immunocytochemical detection of opioid peptides in the cortex has been limited. Using antisera to enkephalin and bovine adrenal medullary peptide, both fragments of proenkephalin, and an antiserum to dynorphin A, a fragment of prodynorphin, we now describe the regional and laminar distribution of a widespread population of olfactory cortical and neocortical cell bodies and fibers with opioid immunoreactivity in rats. Neurons stained with each antiserum are distributed bimodally in layers II and III and V and VI of neocortex as well as in layers II and III of olfactory cortex. The widespread distribution and heterogeneous morphology of cortical cells containing proenkephalin and dynorphin-A immunoreactivity suggest that opioid peptide-containing neurons may influence the functioning of local, commissural, and projection neurons in rat cerebral cortex.

Effects of prenatal progesterone on the development of pyramidal cells in rat cerebral cortex

Pregnant rats received daily injections of 6 or 40 mg/kg progesterone or vehicle only from days 1 to 16 of gestation. The morphology of pyramidal cells in the parietal cortex of the offspring on days 5 and 25 was assessed after staining by the Golgi technique. At postnatal day 5 the cells from both progesterone groups showed a 16% increase in branching of basal dendrites but no change in dendritic spread or cell diameter. At day 25 the number of spines in the apical dendrites of layer IV and V cells were increased 24% in the low-dose group and 36% in the high-dose group. Moreover, the high-dose group showed a significant increase in brain weight on day 25. The amplitude and latency of the cortical evoked potentials on day 5 were not altered by the progesterone treatment. We conclude that progesteone can influence cortical cell morphology but there was no evidence for modification of developing somatosensory pathways.

Functional and ultrastructural changes during ACTH-induced early differentiation of cortical cells of human fetal adrenals in primary cultures

Early events during ACTH-induced differentiation of cortical cells of human fetal adrenals in primary cultures were studied by electron microscopy and steroid analysis. In undifferentiated cortical cells, the basal secretion of steroids was very low. The first sign of ACTH stimulation was a marked increase in pregnenolone sulfate secretion during the first 24 hr, indicating the activation of “pregnenolone synthetase” enzyme. The main shift towards differentiated function occurred during the second and third days of stimulation, shown by increased secretion of ll-deoxycortisol, corticosterone, cortisol, and dehydroepiandrosterone sulfate, while the pregnenolone sulfate concentration decreased. Aldosterone secretion increased only very slightly and slowly during ACTH stimulation. The first change in the morphology of cortical cells was the rounding of the cells during the first 24 hr. Ultrastructurally this was seen by a transformation of plasma membrane into microvillous projections and a loosening of the cell connections. The main functional activation of cortical cells was reflected later as increased smooth endoplasmic reticulum membranes.

Reversible Changes in Adrenal Cortical Cell Morphology and Plasma Hydroxycorticosteroids During Freshwater Portion of the Spawning Journey of Atlantic Salmon (Salmo salar)

Adrenal cortical tissue taken from Atlantic salmon netted in the estuary of the Miramichi River, New Brunswick, at three stages of gonadal activity showed increasing hyperplasia from July to October, with varying degrees of regression or degeneration by the following April. Adrenal cortical cells in April fish contained a characteristic paranuclear dense body, the light and electron microscopic appearances of which are described and discussed. Levels of 17-hydroxycorticosteroids in the plasma almost doubled from July to October and returned to July values by the following April. The presence of these cyclic changes in Atlantic salmon and their absence in Pacific salmon are discussed. Data indicate that genetic factors may be important in determination of the capacity for multiple spawning journeys by some Atlantic salmon.