The effect of ageing on the SIF-cells in the hypogastric (main pelvic) ganglion of the rat.

The effect of ageing on SIF-cells was studied by the formaldehyde-induced fluorescence (FIF) method and by electron microscopy (EM). Microspectrofluorimetry was used to record emission spectra in FIF preparations. In newborn and in young adult (8--12 weeks) rats a single type of SIF-cell emitting greenish-yellow FIF was found while in aged rats a second type of SIF-cell emitting yellowish-brown granular FIF was also present. The intensity of the yellowish-brown FIF was lower than that of the greenish-yellow FIF. Also a few bright cytoplasmic fluorescent areas were occasionally found in some SIF-cells. The distribution of the SIF-cells through the ganglion did not change remarkably with age. In EM after glutaraldehyde-fixation in newborn and in young adult rats two types of small granule-containing (SGC) cells were distinguished according to the size of the dense cored vesicles, 1) 50--150 nm and 2) 50--250 nm. In aged rats, a third type of SGC-cells containing 50 x 250 nm elongated dense core vesicles could also be distinguished. After KMnO4-fixation in newborn and in young adult rats the classification was identical with glutaraldehyde-fixation. In aged rats three types of storage granules were found after KMnO4, 1) 100--300 nm empty vesicles and 2) 100--300 nm vesicles with small dense core, 3) 100--500 nm irregular in shape and filled with electron opaque material with a more dense core.