[Structure of the palisade nerve fibers of the sinuous hair after cutting the infraorbital nerve]. / Struktura palisadnykh nervnykh volokon sinuoznykh volos posle pererezki podglaznichnogo nerva.

The state of the palisade neural fibers (PNF) in the connective tissue of the internal follicle of the cat sinuous hair has been studied after the infraorbital nerve had been cut. Denervation of the sinuous hair is demonstrated to result in certain destructive changes in the PNF. Two days after the operation, cytoplasm becomes more dense, mitochondria undergo destruction, large vacuoles appear in the neural terminals. In the receptory specialized cells, as well as in the neural fiber lemmocytes, the number of the large vacuoles increases, electron opaque bodies appear. On the 7th day after the operation maximal destructive changes are noted. In 30 days after cutting the nerve, regeneration of the neural fibers, the PNF including, begins. In this connection the fate of the specialized cells after destruction of the receptor and their participation in the regenerative process is discussed. The data obtained demonstrate that there are some important functional connections between the axons and the specialized PNF cells. This is necessary to maintain the differentiated state of the receptor in question.

[Cholinesterase activity in the Pacinian corpuscles in denervation and the application of colchicine to the nerve]. / Aktivnost' kholinesteraz tel'tsakh Pachini pri ikh denervatsii i applikatsii kolkhitsina na nerv.

In the Pacinian corpuscles, cholinesterase activity was predominantly revealed along the plasma membrane and in the cytoplasm of the inner core cells. A faint quantity of histochemical end product was detected in the axis cylinder. An increased cholinesterase activity was found after the nerve transection. This change coincides in time with phagocytosis of degenerated axis cylinder by the inner core cells. A decrease in cholinesterase activity was observed in the Pacinian corpuscles after colchicine application to the nerve. This effect may be due to either the blockade of axoplasmic transport of cholinesterase in afferent nerve or/and to the elimination of the trophic influence exerted by the nerve on the cholinesterase activity in the inner care cells.

[Ultrastructure of rat skeletal muscle fibers during prolonged static loading]. / Ul'trastruktura skeletnykh myshechnykh volokon krys pri dlitel'noi staticheskoi nagruzke.

Ultrastructural characteristics of the rat skeletal muscle fibers was studied under a prolonged static loading. Disruption of the mitochondrial membranes, desintegration and lysis of myofibrils, desorganization of the T-system and Z-bands were revealed. Destructive processes were accompanied with the physiological reparative regeneration evidenced by a large number of polysomes and accumulation of myofibrils at the peripheral zone of the muscle fibre. The satellite cells with poorly developed organells were revealed in cytoplasm. Mitotic figures were present in the satellite cells. Clusters of the satellite cells were revealed in the interstitial connective tissue with their successive differentiation into mature muscle fibres. Possible mechanisms of the skeletal muscle fibre formation were discussed.

[Possible extraepithelial precursors of Merkel cells in the sinus hairs in the cat]. / Vozmozhnye vneépitelial'nye predshestvenniki kletok Merkelia sinusoznykh volos koshki.

Numerous Merkel cells are situated among the epithelial cells of the hair follicle of sinus hairs. Many of them are in contact with sensitive nerve terminals and differ from the epithelial cells by the presence in the cytoplasm of specific granules concentrated in the region of contact with nerve terminals. In the connective tissue of sinus hairs of 8-9 weeks old embryos and newborn kittens there were found the cells surrounded by the basal membrane and differing from the Schwann's cells of palisade system and flesh nerve fibers. These extraepithelial cells have common structural features with the Merkel cells situated in the epithelium and are the most probable candidates for the role of their precursors.

[Tactile (Merkel) cells of the sinuous hairs of cats following colchicine application to nerves]. / Osiazatel'nye kletki (Merkelia) sinuoznykh volos koshki pri applikatsii kholkhitsina na nerv.

The state of the tactile cells (Merkel's cells) in epithelium of the internal follicle in the cat sinuous hairs is controlled by sensitive neurons. This statement, derived from the experiments on denervation, was analysed in the investigation when colchicine (an agent blocking axoplasmic transport) was applied on the nerve. Thirty and 60 days after colchicine effect a statistically important decrease in the number of the tactile cells with certain changes in their structure (cytoplasmic consolidation, changes in density of specific granules, increasing number and size of vacuoles) was registered. In epithelium of the internal hairy follicle a contact of the tactile cells with tactile menisci was followed. As in myelin neural fibres of the internal hairy follicle connective tissue, certain signs of destruction, resulting from blockade of colchicine-induced axoplasmic transport, were noted. Participation of the axoplasmic transport in the neurosensory control for the state of the tactile cells is discussed together with the changes described.

[Differentiation of the sartorius muscle during frog ontogeny]. / Differentsirovka portniazhnoi myshtsy liagushki v ontogeneze.

Stages of morphological differentiation of muscular fibres in the musculus sartorius were studied at light optic and electron microscopic levels on tadpoles and mature frogs (Rana ridibunda). Three stages were detected in the development of the muscle--stage of mature myotubes, stage of young and mature fibres. At the 29th stage of development, the sarcomere length is statistically greater, at subsequent stages it is smaller and does not practically differ from that of mature animals. The T-tubes thickness and the A-discs width in the tadpole muscular fibres at different stages of development and those of mature animals do not differ statistically. Muscular differentiation and acquirement of features peculiar for mature animals continue after metamorphosis is completed.

[Tactile cells (Merkel cells) during degeneration of cat sinuous hairs]. / Osiazatel'nye kletki (Merkelia) pri denervatsii sinuoznykh volos koshki.

Degeneration of the tactile cells in epithelium of the cat sinuous hairs after sectioning the infraorbital nerve manifests itself as cytoplasmic vacuolization and induration with electron opaque bodies in it, changes in nuclear configuration and in chromatin density. At all stages of the experiment the tactile cells were practically observed demonstrating various degenerative signs. On the 45th day after sectioning the tactile cells disappeared completely. Structural changes in the tactile cells were preceded by degeneration and complete disappearance of tactile menisci from epithelium of the sinuous hairs. Perhaps, sensitive innervation is necessary to maintain differential status of the tactile cells in epithelium.

[Study of individual Pacinian corpuscle mechanoreceptors following application of colchicine to a nerve]. / Izuchenie odinochnykh mekhanoretseptorov telets Pachini pri applikatsii kolkhitsina na nerv.

Colchicine application to the cat caudal mesenteric nerve containing sensory fibers for single mechanoreceptors (Pacinian corpuscles) causes degeneration of the axis cast of the nerve endings. Ultrastructural changes in the receptors showed no difference from the axonal degeneration after the nerve section but the rate of degeneration was considerably slower. Ultrastructural, electrophysiological, and biochemical changes occurring in the Pacinian corpuscles were not the result of direct action of colchicine, but appeared to be realized through the nerve by the axoplasmic transport block. It is suggested that the receptor's structure is under the sensory neuron neurotrophic control.

[Degeneration of the laminated corpuscles (of Vater--Pacini) following colchicine application to a nerve]. / Degeneratsiia sloistykh telets (fatera--Pachini) pri applikatsii kolkhitsina na nerv.

Laminated pacinian corpuscles from the cat mesentery have been studied morphologically and morphometrically after nerve section and colchicine application to the nerve and the results obtained are represented. Similar interventions in the nerve produce changes in the receptors resembling those of wallerian type degeneration, degeneration rate after sectioning being higher than after colchicine application. At early stages after colchicine application the internal cone and its nuclei increase in size. The data obtained suggest the nuclei of the internal cone to be under neurotrophic control of the sensory neuron that might be realized via axoplasmic transport of substances.