Morphological and ultrastructural aspects of the innervation of rat ureter

The fine innervation of rat ureter has been studied by means of hystological and electron microscopic technique. Different thickness of the different layers of the ureter have been observed. Nerve filaments with minor proportion of myelinic fibres are found in the adventitious layer. Amyelinic fibres, with very fine collaterals whose terminal portion could not be seen, exist in the muscular layer between the external longitudinal fibres and the internal circular ones. Nerve fibres are rarely observed in the centre of the internal circular layer, although it is possible to see terminal buttons, with neural tubules and vesicular formation. These buttons have been observed in some cases beside the muscular membranes, given rise to the hypothetical existence of a synaptic relationship between both membranes. The presence of fine amyelinic filaments, underneath the basal membranes, have also been shown. No ganglionic structure has been observed in the various layers of the ureter, or nerve elements in mucosa.