Flávio Paulo de Faria

Ultrastructural and cytochemical identification of megasome in Leishmania (Leishmania) chagasi

The present work showed the presence of a megasome in Leishmania (Leishmania) chagasi amastigotes. Transmission electron microscopy analysis of ultrathin serial sections and three-dimensional reconstruction allowed visualization of large structures in amastigote forms of L. (L.) chagasi and a multivesicular tubule–lysosome structure in metacyclic promastigotes. Morphometric data showed that the relative volume occupied by the megasome and the multivesicular tubule (MVT)–lysosome structures was about 5% and 3.2%, respectively, in amastigotes and promastigotes of L. (L.) chagasi. Further characterization of the megasome in L. (L.) chagasi amastigotes was carried out by immunolabeling of cysteine proteinase, whereas the lysosomal content of amastigotes and promastigotes was confirmed by arylsulfatase cytochemistry.

Light microscopy and computer three-dimensional reconstruction of the blood capillaries of the enamel organ of rat molar tooth germs

We performed a light microscope and a computer three‐dimensional reconstruction study of serial sections of the molar enamel organ of 3‐ and 5‐day‐old rats perfused with Indian ink through the arterial system. The tooth germs were fixed in Bouins solution, embedded in paraffin, sectioned and stained with haematoxylin and eosin. For the three‐dimensional reconstruction, light micrographs of the serial sections were digitized, and aligned using the serial EM Align software downloaded from http://synapses.bu.edu/tools/. After alignment, the boundaries of the India‐ink‐filled blood vessels were manually traced with a mouse using the software IGL trace (version 1.26b), also downloaded from the above website. After tracing, a three‐dimensional representation of the blood vessel contours was generated in a VRML format and visualized with the help of the software Cortona Web3D viewer (version 4.0) downloaded from http://www.parallelgraphics.com/products/cortona/. Our results showed that in regions where ameloblasts are polarized the capillaries are arranged in three distinct levels: (1) penetrating and leaving capillaries in relation to the outer enamel epithelium; (2) capillaries crossing and branching inside the stellate reticulum; and (3) capillaries branching and anastomosing profusely within the stratum intermedium, thereby forming an extensive capillary plexus intimately associated with the cells of the stratum intermedium. The existence of a conspicuous capillary plexus intermingled with cells of the stratum intermedium, as shown in our results, suggests that some molecules produced by cells of the stratum intermedium could be released into the capillary plexus and thereafter carried to the dental follicle.

Morphometric aspects of the human hypoglossal nerve in adults and the elderly

AIM Perform a morphometric analysis of the myelinic fibers of the right hypoglossal nerve, in two age groups; to verify quantitative changes as a result of the aging process. STUDY DESIGN Anatomic. MATERIAL AND METHOD A 1 cm fragment of the right hypoglossal nerve was collected from 12 male corpses without any medical history of diseases such as: diabetes, alcoholism, and malignant neoplasia. The sample was divided in two groups: group with six corpses under sixty years old (adult), and another group with six corpses sixty years old or above (elderly). The material was fixed at 2.5% glutaldehyde and 2% paraformaldehyde solution; post-fixed at 2% osmium tetroxide; dehydrated with increasing ethanol concentrations, and included in epoxy resin. Semi-thin sections of 0.3 microm were obtaining, colored in 1% toluidine blue, and evaluated with light microscope combined with image analyzing system. The following morphometric data were quantified: intraperineural transversal section area, number, and diameter of the myelinic fibers. RESULTS The intraperineural area of the hypoglossal nerve was similar in both age groups (p=0.8691). The average area in the adult group was 1.697 mm2 and in the elderly group it was 1.649 mm2. The total number of myelinic fibers of the hypoglossal nerve was similar in both age groups (p=0.9018). The adult group presented an average of 10,286 +/- 2,308 myelinic fibers, and the elderly group presented an average of 10,141 +/- 1,590 myelinic fibers. A bimodal distribution of the myelinic fibers was observed, with a significant peak on the 9 microm fibers, and another smaller peak on the 2 microm fibers. CONCLUSION The intraperineural area and the total number of myelinic fibers of the right hypoglossal nerve are similar in both age groups.

replacement of asymmetric synaptic Profiles in the Molecular layer of Dentate gyrus Following cycloheximide in the Pilocarpine Model in rats

Mossy fiber sprouting is among the best-studied forms of post-lesional synaptic plasticity and is regarded by many as contributory to seizures in both humans and animal models of epilepsy. It is not known whether mossy fiber sprouting increases the number of synapses in the molecular layer or merely replaces lost contacts. Using the pilocarpine (Pilo) model of status epilepticus to induce mossy fiber sprouting, and cycloheximide (CHX) to block this sprouting, we evaluated at the ultrastructural level the number and type of asymmetric synaptic contacts in the molecular layer of the dentate gyrus. As expected, whereas Pilo-treated rats had dense silver grain deposits in the inner molecular layer (IML) (reflecting mossy fiber sprouting), pilocarpine + cycloheximide (CHX + Pilo)-treated animals did not differ from controls. Both groups of treated rats (Pilo group and CHX + Pilo group) had reduced density of asymmetric synaptic profiles (putative excitatory synaptic contacts), which was greater for CHX-treated animals. For both treated groups, the loss of excitatory synaptic contacts was even greater in the outer molecular layer than in the best-studied IML (in which mossy fiber sprouting occurs). These results indicate that mossy fiber sprouting tends to replace lost synaptic contacts rather than increase the absolute number of contacts. We speculate that the overall result is more consistent with restored rather than with increased excitability.

Aspectos morfométricos do nervo hipoglosso humano em adultos e idosos

OBJETIVO: Realizar analise morfometrica das fibras mielinicas do nervo hipoglosso direito, em dois grupos etarios, com a finalidade de verificar modificacoes quantitativas decorrentes do processo de envelhecimento. FORMA DE ESTUDO: anatomico. MATERIAL E METODO: Foi coletado fragmento de 1cm do nervo hipoglosso direito de 12 cadaveres do sexo masculino, sem antecedentes para doencas como diabetes, alcoolismo e neoplasia maligna. A amostra foi dividida em dois grupos: grupo adulto (idade inferior a 60 anos), composto por seis cadaveres; grupo idoso (idade igual ou superior a 60 anos), composto por seis cadaveres. O material foi fixado em solucao contendo 2,5% de glutaraldeido e 2% de paraformaldeido; pos-fixado em tetroxido de osmio 2%; desidratado em concentracoes crescentes de etanol e incluido em resina epoxi. Cortes semifinos de 0,3¼m de espessura foram obtidos, corados com azul de toluidina a 1% e avaliados em microscopio de luz acoplado a sistema analisador de imagens. Os seguintes dados morfometricos foram quantificados: area de seccao transversal intraperineural, numero e o diâmetro das fibras mielinicas. RESULTADOS: A area intraperineural do nervo hipoglosso foi semelhante nos dois grupos etarios (p=0,8691). A media da area no grupo adulto foi de 1,697 mm2, e no grupo idoso foi de 1,649 mm2. O numero total de fibras mielinicas do nervo hipoglosso foi semelhante nos dois grupos etarios (p=0,9018). O grupo adulto apresentou media de 10.286 ± 2308 fibras mielinicas e o grupo idoso apresentou media de 10.141 ± 1590 fibras mielinicas. Foi observada distribuicao bimodal das fibras mielinicas, com pico acentuado nas fibras de 9¼m e outro menor nas fibras de 2¼m. CONCLUSAO: A area intraperineural e o numero total de fibras mielinicas do nervo hipoglosso direito e semelhante nos dois grupos etarios.

COMPARATIVE AND MORPHOLOGIC EVALUATION OF EFFECTS OF ASPIRIN AND RANITIDINE ON WOUND REPAIR OF GASTRIC MUCOSA

RESUMEN: Esta investigacion se realizo con el objetivo de verificar los efectos comparativos de la aspirina y de la ranitidina en la recomposicion de la mucosa gastrica despues de una agresion quirurgica. La incision quirurgica, dentro de patrones definidos, fue efectuada en la mucosa gastrica de 12 ratones divididos en 3 grupos: placebo (PG), aspirina (AG) y ranitidina (RG). Las paredes gastrica y abdominal fueron suturadas en dos planos. A los ratones de los grupos PG, AG y RG se le administraron diariamente, por via intragastrica, 1ml de agua destilada, 250 mg/kg de aspirina y 25 mg/kg de ranitidina, respectivamente. Los estudios de la recomposicion de la incision en la mucosa en el 7 dia pos-operatorio, a traves de las microscopias de luz y electronica de barrido, nos mostraron una reepitelizacion del tejido de granulacion y de las celulas del epitelio que envuelven los bordes de la incision quirurgica. La importancia de las alteraciones fue observada de forma decreciente en la mucosa gastrica en los grupos AG, PG y RG.