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Morales E Horn R Pastor LM Santamaría L Pallarés J Zuasti A Ferrer C Canteras M 《Histology and histopathology》2004,19(2):445-455
In this study, we examined the age-related changes on morphometric parameters and ultrastructure of seminiferous tubules, and on the expression of extracellular matrix proteins in lamina propria of Syrian hamsters. A significant decrease in the percentage of normal tubules and an increase in the percentage of hypospermatogenic and arrested maturation tubules was observed with aging. Aged animals showed a decrease in tubular diameter, tubular lumen, seminiferous epithelium volume and total tubular volume. However, the total length of seminiferous tubules was significantly increased with aging. The most important ultrastructural changes with aging were the thickening of the lamina propria, the presence of diverse abnormalities in the spermiogenesis process, degeneration of germ cells, and vacuolization and flattening of Sertoli cells showing abundant lipofucsin droplets and residual bodies. Laminin immunoreactivity was found along the lamina propria of seminiferous tubules both in young and aged animals. Fibronectin immunoreactivity was found along the lamina propria and blood vessels. Both laminin and fibronectin total volume of immunostaining per testis was increased in aged hamsters. In conclusion, the age-related changes in seminiferous tubules of hamster include: a decrease in tubular width and an increase in tubular length; widening of the lamina propria caused by a more extensive connective matrix between the peritubular cells and the basal membrane; and a strong disarrangement of the seminiferous epithelium, including germ cell degeneration and important alterations in both spermiogenesis and Sertoli cell structure. 相似文献
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The lesion of the rat substantia nigra pars compacta dopaminergic neurons as a model for Parkinson's disease memory disabilities 总被引:6,自引:0,他引:6
Da Cunha C Angelucci ME Canteras NS Wonnacott S Takahashi RN 《Cellular and molecular neurobiology》2002,22(3):227-237
1. In this article we review the studies of memory disabilities in a rat model o Parkinson's disease (PD).2. Intranigral administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to rats causes a partial lesion in the substantia nigra, compact part (SNc) and a specific loss of dopamine and its metabolites in the striatum of rats.3. These animals present learning and memory deficits but no sensorimotor impairments, thus modeling the early phase of PD when cognitive impairments are observed but the motor symptoms of the disease are barely present.4. The cognitive deficits observed in these animals affect memory tasks proposed to model habit learning (the cued version of the water maze task and the two-way active avoidance task) and working memory (a working memory version of the water maze), but spare long-term spatial memory (the spatial reference version of the Morris water maze).5. The treatment of these animals with levodopa in a dose that restores the striatal level of dopamine does not reverse these memory impairments, probably because this treatment promotes a high level of dopamine in extrastriatal brain regions, such as the prefrontal cortex and the hippocampus.6. On the other hand, the adenosine receptor antagonist, caffeine, partly reverse the memory impairment effect of SNc lesion in these rats. This effect may be due to caffeine action on nigrostriatal neurons, since it induces dopamine release and modulates the interaction between adenosine and dopamine receptor activity.7. These results suggest that the MPTP SNc-lesioned rats are a good model to study memory disabilities related to PD and that caffeine and other selective A(2A) adenosine receptor antagonists are promising drugs to treat this symptoms in PD patients. 相似文献
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A wide-ranging examination of plastid (pt)DNA sequence homologies within
higher plant nuclear genomes (promiscuous DNA) was undertaken. Digestion
with methylation-sensitive restriction enzymes and Southern analysis was
used to distinguish plastid and nuclear DNA in order to assess the extent
of variability of promiscuous sequences within and between plant species.
Some species, such as Gossypium hirsutum (cotton), Nicotiana tabacum
(tobacco), and Chenopodium quinoa, showed homogenity of these sequences,
while intraspecific sequence variation was observed among different
cultivars of Pisum sativum (pea), Hordeum vulgare (barley), and Triticum
aestivum (wheat). Hypervariability of plastid sequence homologies was
identified in the nuclear genomes of Spinacea oleracea (spinach) and Beta
vulgaris (beet), in which individual plants were shown to possess a unique
spectrum of nuclear sequences with ptDNA homology. This hypervariability
apparently extended to somatic variation in B. vulgaris. No sequences with
ptDNA homology were identified by this method in the nuclear genome of
Arabidopsis thaliana.
相似文献
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A survey was conducted to determine the levels of fumonisins B1 and B2 in corn and corn-based products available in Colombia
for human and animal consumption. A total of 120 samples were analyzed by acetonitrile-water extraction, cleanup with a strong-anion-exchange
column, and liquid chromatography with o-phthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. The
samples of corn and corn-based products for animal intake were taken at different feed manufacturing plants, whereas the samples
used for human foods where purchased from local retail stores. The number of positive samples for fumonisin B1 was 20.0% higher
in corn and corn-based products for animal intake (75.0%) than in corn and corn-based products for human consumption (55.0%).
The levels of fumonisin B1 were also higher in corn and corn-based products for animal intake (mean = 694 μg/kg; range = 32–2964
μg/kg), than in corn and corn-based products for human intake (mean = 218 μg/kg; range = 24–2170 μg/ kg). The incidence and
levels of fumonisin B2 were lower than those for fumonisin B1. Corn and corn-based products for animal consumption had an
incidence of fumonisin B2 of 58.3%, with a mean value of 283 μg/kg, and a range of 44–987 μg/kg. The incidence of fumonisin
B2 in corn-based products for human intake was 35.0%, with a mean value of 118 μg/kg and a range of 21–833 μg/kg. The highest
incidence and levels of fumonisins were found in samples of hominy feed, with concentrations ranging from 86 to 2964 μg/kg
fumonisin B1 and 57 to 987 μg/kg fumonisin B2. 相似文献
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Pastor LM Sánchez-Gascón F Girona JC Bernal-Mañas CM Morales E Beltrán-Frutos E Canteras M 《Histology and histopathology》2006,21(12):1309-1319
The ultrastructural changes of elastic fibres in emphysematous lungs have been studied in men, but few works exist on this topic in experimental emphysematous animals. In this paper, the morphogenesis of emphysema and alterations of the elastic fibres produced by the instillation of papain are described by light and electron microscopy. Wistar rats were instilled through the trachea with papain at a rate of 3 mg/100 g animal weight. The animals were sacrificed 12 h, 3 days, 10 days and 60 days after enzyme instillation. The "Mean Linear Intercept" (MLI), the "Number of fenestrations/respiratory units" (NF) the "Number of macrophages per mm of alveolar wall" (NM) and the "Number of respiratory unit/mm2" (RU), both in the control and experimental groups were studied. Two months after treatment, the experimental group showed a strong increase in the MLI (p<0.001) and NF (p<0.001), and a diminished number of RU (p<0.05) compared with the control group. Partial correlation analysis showed a positive correlation only between MLI and NF. Twelve hours after papain instillation an inflammatory response was observed, the elastic fibres were ruptured, while the microfibrilar component remained. New formations of eulanin elastic fibres were observed three days post papain instillation. After ten days the interalveolar oedema had disappeared and the elastic fibres were of normal morphology although irregular groups of strips of elastic fibres were evident. A mixed pattern of panlobular, centrilobular and normal lung zones were observed. Two months after papain instillation abundant accumulations of elastic fibres of irregular outline were observed associated to collagen fibres. In conclusion, the morphometric parameters studied showed a significant progression of the emphysema. The strong correlation between NF and MLI suggested that papain-induced emphysema is principally caused by breaches of the alveolar walls. The results seem to point to a very abnormal remodelling process associated with elastic fibre regeneration, although there were no signs of destruction of these new fibres formed in emphysematous rat lung induced by papain. 相似文献
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F J Salazar J García-Esta? L F Carbonell J A Mu?oz M Canteras T Quesada 《Revista Espanola de Fisiología》1983,39(2):161-167
Hypertension was induced in Wistar rat by means of a clip in the left renal artery. After two weeks (acute stage) and sixteen weeks (chronic stage) the animals had a significant increase in arterial pressure (AP) and plasma renin activity (PRA). At both stages, nephrectomy or revascularization of the ischemic kidney returned AP and PRA to the normal level, both in the short term (1 day) and long term (60 days). 相似文献
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ERVĪNS LUKŠEVIČS PER E. AHLBERG ĢIRTS STINKULIS JEĻENA VASIĻKOVA IVARS ZUPIŅŠ 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2012,45(3):356-370
Luk?evi?s, E., Ahlberg, P.E., Stinkulis, ?., Vasi?kova, J. & Zupi??, I. 2011: Frasnian vertebrate taphonomy and sedimentology of macrofossil concentrations from the Langsēde Cliff, Latvia. Lethaia, Vol. 45, pp. 356–370. The siliciclastic sequence of the Upper Devonian of Kurzeme, Western Latvia, is renowned for abundant vertebrate fossils, including the stem tetrapods Obruchevichthys gracilis and Ventastega curonica. During the first detailed taphonomic study of the vertebrate assemblage from the Ogre Formation cropping out at the Langsēde Cliff, Imula River, abundant vertebrate remains have been examined and identified as belonging to one psammosteid, two acanthodian and three sarcopterygian genera; the placoderm Bothriolepis maxima dominates the assemblage. Besides fully disarticulated placoderm and psammosteid plates, separate sarcopterygian scales and teeth, and acanthodian spines, partly articulated specimens including complete distal segments of Bothriolepis pectoral fins, Bothriolepis head shields and sarcopterygian lower jaws have been found. The size distribution of the placoderm bones demonstrates that the individuals within the assemblage are of approximately uniform age. Distinct zones have been traced within the horizontal distribution of the bones. These linear zones are almost perpendicular to the dominant dip azimuth of the cross‐beds and ripple‐laminae and most probably correspond to the depressions between subaqueous dunes. Concavity ratio varies significantly within the excavation area. The degree of fragmentation of the bones and disarticulation of the skeletons suggest that the carcasses were reworked and slightly transported before burial. Sedimentological data suggest deposition in a shallow marine environment under the influence of rapid currents. The fossiliferous bed consists of a basal bone conglomerate covered by a cross‐stratified sandstone with mud drapes, which is in turn overlain by ripple laminated sandstone, indicating the bones were buried by the gradual infilling of a tidal channel. All the Middle–Upper Devonian vertebrate bone‐beds from Latvia are associated with sandy to clayey deposits and have been formed in a sea‐coastal zone during rapid sedimentation episodes, but differ in fossil abundance and degree of preservation. □Agnathans, Devonian, facies analysis, fish, fossil assemblage, palaeoenvironment. 相似文献