Neonatal anoxia in rats: hippocampal cellular and subcellular changes related to cell death and spatial memory.

Neonatal anoxia in rodents has been used to understand brain changes and cognitive dysfunction following asphyxia. This study investigated the time-course of cellular and subcellular changes and hippocampal cell death in a non-invasive model of anoxia in neonatal rats, using Terminal deoxynucleotidyl transferase-mediated dUTP Nick End Labeling (TUNEL) to reveal DNA fragmentation, Fluoro-Jade® B (FJB) to show degenerating neurons, cleaved caspase-3 immunohistochemistry (IHC) to detect cells undergoing apoptosis, and transmission electron microscopy (TEM) to reveal fine ultrastructural changes related to cell death. Anoxia was induced by exposing postnatal day 1 (P1) pups to a flow of 100% gaseous nitrogen for 25 min in a chamber maintained at 37 °C. Control rats were similarly exposed to this chamber but with air flow instead of nitrogen. Brain changes following anoxia were evaluated at postnatal days 2, 14, 21 and 60 (P2, P14, P21 and P60). In addition, spatial reference memory following anoxia and control treatments was evaluated in the Morris water maze, starting at P60. Compared to their respective controls, P2 anoxic rats exhibited (1) higher TUNEL labeling in cornus ammonis (CA) 1 and the dentate gyrus (DG), (2) higher FJB-positive cells in the CA2-3, and (3) somato-dendritic swelling, mitochondrial injury and chromatin condensation in irregular bodies, as well as other subcellular features indicating apoptosis, necrosis, autophagy and excitotoxicity in the CA1, CA2-3 and DG, as revealed by TEM. At P14, P21 and P60, both groups showed small numbers of TUNEL-positive and FJB-positive cells. Stereological analysis at P2, P14, P21 and P60 revealed a lack of significant differences in cleaved caspase-3 IHC between anoxic and control subjects. These results suggest that the type of hippocampal cell death following neonatal anoxia is likely independent of caspase-3 activation. Neonatal anoxia induced deficits in acquisition and performance of spatial reference memory in the Morris water maze task. Compared to control subjects, anoxic animals exhibited increased latencies and path lengths to reach the platform, as well as decreased searching specifically for the platform location. In contrast, no significant differences were observed for swimming speeds and frequency within the target quadrant. Together, these behavioral results indicate that the poorer performance by anoxic subjects is related to spatial memory deficits and not to sensory or motor deficits. Therefore, this model of neonatal anoxia in rats induces hippocampal changes that result in cell losses and impaired hippocampal function, and these changes are likely related to spatial memory deficits in adulthood.

Histological and histomorphometrical alterations of the periodontal ligament in gerbils submitted to teeth extraction.

This study verified the effect of unilateral teeth extraction on the periodontal ligament in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50 g had induced occlusal alterations by upper left molar extractions while the other ten animals, only submitted to surgical stress, were considered as controls. The periodontal ligament was characterized by qualitative and quantitative analysis, histological description and histomorphometric quantification. Significant alterations were observed on the left side of the experimental group (P < 0.05), the hypofunctional region, when it was compared with the contralateral side and the corresponding region of the control group. Two months after occlusal alterations induced by unilateral teeth extraction, atrophic histological alterations and a decrease in the periodontal space on the ipsilateral side characterized the periodontal ligament. In this study it was possible to conclude that the gerbil can be used in experimental models attempting to correlate the periodontium's biological response to various mechanical stresses, as the periodontal ligament was shown to be highly sensitive to occlusal alterations.

Scanning electron microscopy of angioarchitecture of palatine gingiva in young rabbits.

The angioarchitecture of young rabbits' palatine gingiva was studied by using the corrosion resin cast method. The vascular corrosion casts were obtained using low viscosity resin (Mercox CL-2B) and were observed with scanning electron microscopy (SEM). The palatine gingiva had areas with various arrangements. The capillaries of the palatine gingiva and interdental papillae had numerous projections, but in the gingival sulcus, the blood vessels were arranged in a flattened network from their capillary extremities. The blood vessels supplying the alveolar bone were also clearly seen.

Light and scanning electron microscopic studies of the angioarchitecture of intrinsic muscle fibers of the anterior rat tongue.

Histological and scanning electron microscopy (SEM) characteristics of the microvasculature of muscle fibers in the anterior third of the adult rat tongue are described. For light microscopy, the specimens were embedded in paraffin and frontal sections were stained with Picro-Sirius. Thick sections were obtained from Spurr embedded samples and stained with toluidine blue solution. For SEM, specimens were obtained by the corrosion cast method and fractured specimens in dimethyl sulfoxide were observed with high-resolution SEM (HRSEM). The blood vessels, enveloped with a thin layer of connective tissue, had fibers running parallel to the muscular fibers. Capillary arterioles were noted following the endomysium, but their lateral branches often ran at right angles to the fibers. The capillary beds were clearly revealed in transverse sections where the individual capillaries appeared ring-like or elliptical in shape. The nuclei of endothelial cell cores could be seen on the vessel surfaces. Collagen fibers type I and III were noted in the connective tissue and in the fibrous layer of vessels.

The arrangement of the trabecular bone in the vestibular surface of the human fetus mandible. A scanning electron microscopy study.

The characteristics of trabecular bone in human fetuses at seven to nine months of intra-uterine life were studied in the vestibular surface of the mental and body portions of the mandible. In the mental portion, many circular trabeculae joined by "bridges" were observed in the alveolar region (AR). In the 8-month old fetus are trabeculae with tortuous disposition in the medium region (MR). Oblique trabeculae with superior and inferior dispositions defining a triangular area (future mental fossae) are verified in 9-month old fetuses. Trabeculae circularly disposed and vascular foramina are present close to the apex of this area. In the basilar region (BR) some trabeculae obliquely oriented are observed disposed near to the mandibular symphysis. The longitudinal bundles of collagen fibers assume an antero-posterior direction. At 9-month age the vascular foramina range from 6 to 20 microns and the osteocyte lacunae ranging from 1 to 4 microns diameter, are present in mandibles from all ages examined. In the body portion the presence of circular trabeculae joined by "bridges" is the main characteristic of the AR. In the MR most of the trabeculae are circular and the longitudinal trabeculae of this region assume an antero-posterior direction. The laminar, antero-posterior and juxtaposed trabeculae lying parallel to mandible base are a characteristic of the BR. The bundles of collagen fibers exhibit the same pattern of the trabeculae. The vascular foramina of the BR are smaller than that of the precedent regions. In the body portion of the mandible from all ages examined the osteocyte lacunae range from 1 to 4 microns in diameter.

Angioarchitectural arrangements in corrosion cast of the nasal septum of the Mongolian gerbil.

The three-dimensional architecture of the vascular network of the nasal septum of the gerbil rat was studied using the corrosive resin cast technique. The angioarchitecture of the nasal septum observed with scanning electron microscopy (SEM) showed that a vascular network is disposed in the lamina propria. The capillaries, arterioles, venules and arteries were closely observed in different areas of the nasal septum mucosa.

Nd:YAG laser effects on the occlusal surface of premolars.

PURPOSE: To evaluate with the scanning electron microscope (SEM) the effects of a pulsed Nd: YAG laser on the occlusal surface of human premolars in vitro. MATERIALS AND METHODS: Twenty normal premolars extracted for orthodontic reasons were used and separated in two groups. Group 1 received the irradiation at 2.0 watts, repetition rate of 20 Hz and 124.3 J/cm2 of energy density during 3 minutes, on the occlusal fissure. Group 2 received the laser irradiation in only half of the fissure. RESULTS: The SEM analysis revealed that in the case of shallow fissures the sealing was total but in narrow and deep fissure the sealing was partial or was in complete.

Three-dimensional angioarchitecture of tongue corrosion casts from normal young rats.

The three-dimensional architecture of the vascular network of the rat's lingual papillae has been studied employing the corrosive resin cast technique. The casts of the microvasculature of these types of papillae (the small conical filiform, true filiform, fungiform and vallate papillae) have been observed under scanning electron microscopy (SEM). The microvascular arrangements of the filiform papillae consist of well-defined simple or twisted capillary loops. The fungiform papillae have a cylindrical form with a central hole, and the capillary network gives shape to the whole papilla. Finally, the capillary bed of the oval-shaped vallate papilla with its characteristic network and small hairpin-like loops was also examined.

Light and scanning electron microscopic study of the palatine mucosa of nine-banded armadillo (Dasypus novemcinctus).

The three-dimensional structure of the lamina propria of the hard and soft palatine mucosa of the nine-banded armadillo was observed by scanning electron microscopy. Sodium hydroxide cell maceration method was applied to demonstrate the architecture of the connective tissue papillae. The palatine mucosa of the armadillo had a triangular shape and measured appr. 6.5 cm length. The hard palate showed 9 transverse palatine plicae while the soft palate was smooth. In the 10% NaOH treated specimens, the lamina propria of the hard palatine mucosa showed numerous connective tissue papillae with a general finger-like shape. These structures were composed by a meshwork of collagen fibers arranged in several directions. On the other hand, the connective tissue papillae of the soft palate mucosa were scattered and small. Numerous openings of glandular ducts with circular or elliptical shape were located in the interplicae area and in the soft palate.

Diameter of axons in the lingual nerve of the mouse. A preliminary investigation.

The lingual nerves from ten mice were examined so that normal axonal populations could be determined. After perfusion fixation, they were removed and processed, and sections were taken from nerves for transmission electron microscopy. The fiber-diameter spectrum of unmyelinated fibers for the mouse lingual nerve is characterized by a unimodal curve with the more pronounced peak in the medium-diameter fiber range (0.28 micron). The spectrum from the myelinated fibers also shows a population of axons of the lingual nerve (0.22-3.2 microns) that reflects different functional specializations. These data establish some baseline values for morphological evaluation of the effects of experimental lingual nerve damage.

Natal teeth in cleft lip and palate patients: a scanning electron microscopy study.

Natal and neonatal teeth may occur in patients up to 30-days after birth. The presence of two neonatal teeth in cleft lip and palate patients is reported in this study describing the structural aspects of the enamel and the dentin, using scanning electron microscopy.

Light and scanning electron microscopic study of the digestive tract in the catfish Pseudoplatystoma Corruscans Agassiz, 1829 (Pisces, Pimelodidae)

O trato digestivo do surubin Pseudoplatystoma corruscans foi estudado morfologicamente utilizando a microscopia de luz e eletrônica de varredura (MEV), além de técnicas histoquímicas. O epitélio estratificado do palato e faringe está constituído de uma camada basal com células indiferenciadas de núcleos elípticos de posiçäo central; uma camada média constituída de células intermediárias indiferenciadas, células gigantes acidófilas e células mucosas; e uma camada superficial de células achatadas. O esôfago apresenta estrutura semelhante, com células gigantes acidóficas menos numerosas e células poilimorfonucleares entre as células da camada basal, ao MEV, o palato evidenciou vários sulcos, sendo que a porçäo superficial está constituída de células hexagonais ou poligonais, em cuja área apical está presente as microcristas. A parte superficial da faringe apresenta células com microcristas dispostas concentricamente. O esôfago mostrou pregas longitudinais complexas, um epitélio estratificado cujas células apresentam microcristas irregulares. Os carbohidratos presentes nas células do tracto digestivo foram identificados como sendo mucosubstâncias neutras e ácidas

Ultrastructural study of the palatine mucosa of the opossum (Didelphis albiventris)

As características das células epiteliais da mucosa palatina do gambá foram descritas utilizando o microscópio eletrônico de transmissäo. O epitélio é do tipo estratificado escamoso queratinizado formado por camadas basal, espinhosa, granulosa e córnea. As células epiteliais basais säo colunares com núcleos basais e contêm mitocôndrias, ribosomos e retículos endoplasmáticos granulares. As células espinhosas säo de forma poligonal e possuem filamentos de 10nm, enquanto as células da camada granulosa apresentam numerosos grânulos de keratohialina. As células córneas säo achatadas, com conteúdo amorfo e contêm distintas micropregas na superfície. Observa-se desmosomos entre as células epiteliais das diferentes camadas

Morphological observations of the sensory nerve endings of the Calomys callosus' lingual mucosa, employing the silver impregnation method

Estudaram-se as características morfológicas das terminaçöes nervosas sensitivas da mucosa lingual de Calomys callosus, empregando-se a técnica de impregnaçäo pela prata. Para a obtençäo das peças, cada animal foi anestesiado com injeçäo intraperitonial de tionembutal sódico. As peças foram fixadas em soluçäo de formalina a 10 por cento por um período de 20 dias à temperatura ambiente e cortes espessos de 40-60 micrometros foram obtidos em criostato Linde. As preparaçöes foram coradas pela técnica de impregnaçäo pela prata. De acordo com os nossos resultados podemos concluir que: 1) todas as regiöes (anterior, média e posterior) da mucosa dorsal da língua de Calomys callosus possuem terminaçöes nervosas sensitivas; 2) as terminaçöes nervosas podem ser simples ou complexas localizando-se no tecido conjuntivo da lâmina própria ou no interior das papilas conjuntivas das papilas filiformes, fungiformes e valadas, 3) as terminaçöes nervosas livres no interior das papilas fungiformes dispöem-se longitudinalmente ou formando uma rede complexa de fibras nervosas terminais

Características tridimensionais da camada aprismática de fissuras de premolares humanos: estudo ao microscópio eletrônico de varredura / Three-dimensional characteristics of enamel \"prismless\" layer of the human premolar fissurae: a scanning electron microscopy study

A estrutura de esmalte aprismático de fissuras de premolares humanos foi observada através de superfícies fraturadas vestíbulo-lingualmente. Os resultados mostraram que a camada aprismática margeia a superfície da fissura em toda extensão. A espessura da camada aprismática é aumentada na porção média da fissura a qual é semelhante aquela encontrada nas superfícies vestibular e lingual. Os cristais de hidroxiapatita dispondo-se paralelamente são claramente vistos em aspectos tridimensionais

Scanning electron microscopy of the lingual mucosa of the nine-banded armadillo, Dasypus novemcinctus.

The lingual mucosa of the nine-banded armadillo, Dasypus novemcinctus, was studied by scanning electron microscopy in order to analyse its morphology. The tongue of the armadillo is long and thin, and has filiform, fungiform and vallate papillae. In the anterior part of the tongue and near the vallate papillae, single or bifurcated filiform papillae are found. The vallate papillae are located on the dorsal surface of the middle third of the tongue, and have two or four slender extremities. The fungiform papillae are elliptical or rounded, and are concentrated mainly on the tip and lateral surface of the tongue, reaching as far as the middle third of the dorsal surface. Their surfaces are flat and smooth on the dorsal side, with some taste pores. Their taste buds are located near the vallum. In the material for which freeze-cracking was used, the epithelial layer showed a characteristic mucosal structure, with many epithelial papillae containing blood vessels and bundles of collagen fibers. The basal epithelial surface of the tongue mucosa showed irregular projections that are rounded or polygonal in shape, with a depression in the center. These depressions varied in diameter.

[Number and thickness of myelinic fibres of the phrenic nerve of young and aged rats]. / Número e espessura de fibras mielínicas do nervo frênico de rato albino jovem e senil.

The phrenic nerve of albino rats was studied for age changes in number of fibres, myelin sheath thickness and axon calibre. There is no significant morphological differences between nerves from young and aged rats and no difference with age was found in the number of fibres, myelin sheath thickness and axon calibre.

Presence of amastigotes in the Weber's lingual salivary gland of Trypanosoma cruzi-infected mice.

The authors studied histopathologically the presence of amastigotes in the Weber's lingual salivary gland of mice infected with RC strain of Trypanosoma cruzi. Amastigotes were found in Weber's gland acini cells, excretory duct cells, intralobular connective tissue, muscle fibers and inside the acini lumen.

[Dentinal surface of root canals. Study of human permanent upper central incisors, using scanning electron microscopy technic]. / Superficie dentinária do canal radicular. Estudo em incisivos centrais superiores permanentes humanos, empregando a técnica de microscopia eletrônica de varredura.

Dentinal surfaces of the root canal in the human permanent incisors were studied by using scanning electron microscope. The teeth were sectioned and fractured longitudinally. Dehydration were made in ethanol, dried, coated with gold and examined in a Jeol scanning electron microscope. The results revealed that the dentinal surface of the root canal of central upper incisor presents numerous foraminae of dentinal tubules. These possess variable diameters being that the smallest ranges from 1 to 2 microns and the greatest ranges from 2.5 to 4 microns. The intertubular dentinal surface is uniform in aspect and the peritubular dentine show several lines on the walls.

On the fine structure of the parotid gland of tufted capuchin monkey, Cebus apella.

The parotid gland of the tufted capuchin monkey (Cebus apella) was examined by scanning and transmission electron microscopy. In general the ultrastructural morphology of this gland appears similar to that described in spider and squirrel monkeys. This study has established that the gland is serous. Acinar cells, which contain a well developed granular endoplasmic reticulum and a prominent GOLGI complex, produce a single secretory material. Myoepithelial cells are present around acini and around intercalated ducts. The intercalated ducts, which are composed of cells that show no evidence of secretory activity, lead into striated ducts.