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 Bouin's 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.

Comparative and morphologic evaluation of aspirin and ranitidine effects on wound repair of gastric mucosa

Esta investigación se realizó con el objetivo de verificar los efectos comparativos de la aspirina y de la ranitidina en la recomposición de la mucosa gástrica después de una agresión quirúrgica. La incisión quirúrgica, dentro de patrones definidos, fue efectuada en la mucosa gástrica de 12 ratones divididos en 3 grupos: placebo (PG), aspirina (AG) y ranitidina (RG). Las paredes gástricas y abdominal fueron suturadas en dos planos. A los ratones de los grupos PG, AG y RG se le administraron diariamente, por vía intragástrica, 1 ml de agua destilada, 250 mg/ka de aspirina y 25 mg/kg de ranitidina, respectivamente. Los estudios de la recomposición de la incisión en la mucosa en el 7º día pós-operatorio, a través de las microscopías de luz y electrónica de barrido, nos mostraron una reepitelización del tejido de granulación y de las células del epitelio que envuelven los bordes de la incisión quirúrgica. La importancia de las alteraciones fue observada de forma decreciente en la mucosa gástrica en los grupos AG, PG y RG