Abstract

Identical, or adjacent, fresh-frozen sections of the vas deferens (guinea pig, cat), uterus and fallopian tube (cat), and nictitating membrane (cat, rabbit) were examined for catecholamines (modified formaldehyde vapor technique) and acetycholinesterase (AChE) activity (thiocholine technique). In the vas deferens and nictitating membrane, the distribution and density of catecholamine-fluorescent nerve tracts were similar in the cat and in time other species, but AChE staining was much more restricted in the corresponding tissues of the cat, whereas it approximated the pattern of catecholamine fluorescence in the other species. Thus, in these cases the species variations in the AChE activities of the peripheral, presumably postganglionic sympathetic nerve fibers reflect those noted previously in the corresponding sympathetic ganghion cells. The uterus and fallopian tube of the cat, on the other hand, showed a much more extensive distribution of fibers having low but definite AChE activity, corresponding with the patterns of those exhibiting catecholamine fluorescence, than noted in the other organs of this species. These findings were considered in terms of the Burn and Rand hypothesis, that the release of norepinephrine from postganglionic adrenergic fibers is mediated or facilitated by acetylcholine. It was concluded that the present results are consistent with the occurrence of such a mechanism in the vas deferens of the guinea pig and nictitating membrane of the rabbit, but probably not in the same organs of the cat: in the cat uterus and fallopian tube, however, the hypothesis could apply. In order to obtain more direct information by this type of approach, it will be necessary to develop methods which permit the definite localization within individual nerve fibers of the transmitters or their related enzymes, by electron microscopy.