Microspectrofluorimetric estimation of the formaldehyde-induced fluorescence of the developing main pelvic ganglion of the rat.

The formaldehyde-induced fluorescence (FIF) of the cytoplasm of individual developing neurons of the main pelvic ganglion was recorded microspectrofluorimetrically in order to follow changes in catecholamine (noradrenaline) content during development. For each ganglion, the fluorescence intensity profile was estimated and shown graphically as columns expressing percentage distribution of relative intensities in different intensity classes. During development, the number of weakly fluorescent neurons increases. Treatment with testosterone shifts the profile towards higher intensities in four- and six-week-old animals. Testosterone affected the main pelvic ganglion but not the superior cervical ganglion. The intensity of the cytoplasmic FIF, which correlates with the catecholamine (noradrenaline) content of the object tissue, showed a tendency to decrease during development. This change was not obvious vy visual observation because of the increase in cell size and the toal bulk of the ganglion. Other possible factors affecting visual observation are discussed.