Morphological and electrophysiological peculiarities of sensory bush-like receptors of the frog urinary bladder

Abstract Results of synchronous morpho-electrophysiological experiments conducted on living bush-like receptors of the urinary bladder of a frog ( Rana temporaria ) and results of their ultrastructural and cytochemical studies are presented in this article. It is demonstrated that these endings are mechanical receptors reacting to tactile stimuli. Rapidly and slowly adapting units are registered. The slowly adapting receptors prevail (94%). Morpho-topographie peculiarities of the rapidly and slowly adapting forms are recorded at the light (optic) level. Different variants of sediment deposits at Ranvier nodes of the myelinated afferent fibers are demonstrated by means of a ferri-ferricyanide technique. In this connection a hypothesis is discussed concerning the existence in bush-like receptors of several generators of impulses converging on to a solitary fiber. The ultrastructure of receptor terminals is demonstrated. Their connection with tissue elements of the organ wall is realized with the help of collagen fibrils braiding the terminals with a dense irregular net. No connections are discovered between terminals and cells with the help of desmosomes. It is supposed that this very interrelation of the receptor terminals with the surrounding tissues ensures a predominance of the slowly adapting forms among them.