[Innervation of the m. sphincter pylori in cats]

The ultrastructure of neuro-muscular relations in m. sphincter pylori of a cat was examined by fixation with CsO4 using imersion and staining of a sample of tissue with uranyl acetate during delydration. There were regular, dense and parallel muscular cells with intersticial spaces in the range of 250 A. Structures with various round and oval forms fitted closely to the smooth muscle cells. They had homogeneous amorphous structure and small electronic density. Nervous bundles with variable size were located in the intersticial spaces. Isolated single nervous fibres were encountered at some sites. Axonic profiles were located from the plasmatic membrane of the muscular cells at a distance of least 430 A. There were contacts with structure similar to the synapses among isolated nervous profiles. There were also nervous profile which contained large (around 1500 A) granular vesicules. The author discuses the type of inervation of m. sphincter pylori as well as the vesicular content of axons.in view of the eventual functional significance.