Morphological integrity of the rat superior cervical ganglion after prolonged incubation in vitro.

The outer capsule of rat superior cervical ganglia is usually removed before in vitro studies are initiated. An ultrastructural study was undertaken to determine if any morphological disruption results as a consequence. Intact ganglia were fixed by either aldehyde immersion or perfusion. Desheathed ganglia were immersed in aldehyde fixative immediately following the removal of the capsule or after a 5-hour incubation period in a modified Krebs-Ringer solution. Ganglionic transmission, monitored by observing the compound postganglionic action potential evoked by periodic preganglionic nerve stimulation during the incubation period, was not diminished. Some minor disruption of mitochondrial cristae was observed in neurons but ganglionic morphology was generally well preserved. These findings support the use of desheathed rat ganglia as a valid in vitro model.