Ultrastructure of motor nerve terminals in the anterior third of Wistar rat tongue.

The nerve terminals of intrinsic muscular fibers of the tongue of adult wistar rats was studied by using silver impregnation techniques, transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HRSEM) to observe the nerve fibers and their terminals. Silver impregnation was done according to Winkelman and Schmit, 1957. For TEM, small blocks were fixed in modified Karnovsky solution, postfixed in 1% buffered osmium tetroxide solution, and embedded in Spurr resin. For HRSEM, the parts were fixed in 2% osmium tetroxide solution with 1/15 M sodium phosphate buffer (pH 7.4) at 4 degrees C for 2 h, according to the technique described by Tanaka, 1989. Thick myelinated nerve bundles were histologically observed among the muscular fibers. The intrafusal nerve fiber presented a tortuous pathway with punctiform terminal axons in clusters contacting the surface of sarcolemma. Several myelinated nerve fibers involved by collagen fibers of the endoneurium were observed in HRSEM in three-dimensional aspects. The concentric lamellae of the myelin sheath and the axoplasm containing neurofilaments interspersed among the mitochondria were also noted. In TEM, myofibrils, mitochondria, rough endoplasmic reticulum, Golgi's apparatus, and glycogen granules were observed in sarcoplasm. It is also noted that the sarcomeres constituted by myofilaments with their A, I, and H bands and the electron dense Z lines. In areas adjacent to muscular fibers, there were myelinated and unmyelinated nerve fibers involved by endoneurium and perineurium. In the region of the neuromuscular junction, the contact with the sarcolemma of the muscular cell occurs forming several terminal buttons and showing numerous evaginations of the cell membrane. In the terminal button, mitochondria and numerous synaptic vesicles were observed.

Effects of the CO2 laser on the mucosa of the hard palate of wistar rats: scanning electron microscopy study

Se estudió los efectos del CO2 en la mucosa del paladar duro de ratas Wistar. Los especímenes fueron fijados en solución de Karnovsky modificado y analizados a través de microscopía electrónica de barrido. La mucosa palatina normal presenta células epiteliales queratinizadas y pliegues de profundidad variable. El área carbonizada reveló gran cantidad de estructuras granuladas y agujeros de diferentes diámetros. La capa epitelial se mostró totalmente carbonizada y condensada en formaciones irregulares. En las áreas fundidas se observaron cráteres resultantes de la solidificación del material fundido y además, formas irregulares en toda su extensión