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Using the electronograms of Pacinian corpuscle capsule of the cat mesentery the authors have studied in details the structure of its layers and lamellae. The thickness of the capsule lamellae ranged between 30 nm-320 nm, the mean width being 150 nm. On the surface they are overlaid by means of lamina basalis. The capsule is formed by circular layers composed, most often, by 1-2 lamellae, less frequently, by larger number of lamellae. The width of the space between the layers of lamellae is 150-820 nm. A number of lamellae is provided with longer or shorter processes. They are directed more often to the adjacent lamella with which they can be also connected by means of membrane specialization. However, they are also directed into the space between individual layers of the capsule. The importance of these processes has not been known. Furthermore, the authors have studied the reciprocal link-up of the lamellae within one layer. The lamellae are connected either side-to-side, by inserting the end of one lamella into the infolding of the other, end-to-side or end-to-end. Rich pinocytotic activity (rich occurrence of caveolae) was observed in the lamellae of the capsule. Therefore the authors are of the opinion that the capsule and its lamellae have not only mechanical significance or the function of the transfer system and filter, but they form an important component (subsystem) of the whole metabolic system in the sensory corpuscle.

The authors studied the ultrastructure of axon processes in simple sensory corpuscles, Herbst and Pacinian corpuscles. They give a description of their shape, topographical localization and relation to organelles. They focused their attention to the incidence of various kinds of vesicles in the processes and at their bases, and the incidence and localization of of mitochondria. The most frequently occurring vesicles are those of medium electron density (clear vesicles), in small numbers there are also dense core vesicles and coated vesicles. The incidence of vesicles is predominantly polarized, i.e. they are situated at the bases of axon processes, opposite the so-called clefts of the inner core. In sporadic cases reach into the processes besides clear vesicles also mitochondria. Direct connection between axon processes and inner core lamellae was not observed. The authors are considering the possible importance of these processes in the transmission of stimuli to the axon. They are of the opinion that further studies are necessary to specify the morpho-physiological relations inside sensory corpuscles.

The first signs of reinnervation of the Pacinian corpuscles have been established at the middle of the second month after nerve crush. The regenerative process pass through two periods. During the first period the progressive increase of the Schwann receptor cells has been observed parallel to the reduction of the regenerating nerve branches. During the second period the reorganization and renewal of the regenerated organelles takes place. Some organelles as dense core vesicles, coated vesicles and microtubules of the receptor nerve fibre show noticeable dynamics. The regeneration has been established only in the preexisting after denervation capsulated remnants of the receptors. After nerve transection the regeneration is prolonged one month later and the less of quantity reinnervated receptors have been observed.