Some cytochemical and cytological features of the so-called SIF cells of the superior cervical ganglion of the rat.

The properties of uptake and storage of dopamine and noradrenaline of the SIF cells of the superior cervical ganglion of the rat were tested, using the radioautographic method. Their ability to store exogenous catecholamines appears very poor under the present experimental conditions, in spite of the great number of storage vesicles they usually contain. This situation may be related either to the absence of a high affinity uptake mechanism in the SIF cell membrane or to a normal saturation of SIF cells in catecholamine. Cytological peculiarities of nerve terminals on SIF cells were pointed out. Dense patches attached to the inner face of the SIF cell membrane suggest a local release of vesicular contents, with further functional implications.