[Variation in the number and size of myelinated nerve fibers regenerated after repeated localized freezing of the sciatic nerve of rats].

The number and size of myelinated fibres have been determined in the nerve to medial head of the gastrocnemius muscle of Rats in which the sciatic nerve had been frozen locally 1 to 5 times at monthly intervals. The contralateral nerve was used as a control. When the measurements were made one month after the last freezing, the number of fibres increased progressively until the 3rd freezing, reaching about 220% of the normal value.

[Iontophoresis of noradrenaline on neurons of the septal, preoptic and anterior hypothalamic areas].

In the Guinea-Pig, iontophoretic application of noradrenaline to neurones in the rostral hypothalsmus has an exciting, inhibitory effect, or is without effect. Responses to noradrenaline of antidromically activated neurones by stimulation of arcuate nucleus-median eminence region are discussed in relation to the liberation of LH.

[Effect of metabolism on the electrical and mechanical activities of the frog atrium].

Due to glycolysis, anaerobic ATP supports normal electrical activity and allows only a reduced but sustained mechanical activity; however, frog myocardium metabolism is mainly aerobic dependent. Krebs cycle provides ATP for both mechanical and electrical acitivites even when glycolysis is inhibited. The close correlation between amplitude of contraction and metabolic state suggests that ATP is a limiting factor of mechanical activity even in normal conditions.

[Modes of appearance of giant spontaneous potentials induced by vinblastine on the isolated preparation of frog muscle].

Vinblastine induces reversible changes of the spontaneous release of ACh at the fro,neuromuscular junction characterized by the appearance of "giant" potentials. These large potentials occur soon after soaking the muscle in Vinblastine and are not consecutive to a large increase of the spontaneous release. They seem to serive from the release of big packets of ACh which could be elaborated from preexistent quantal units.

[Differentiation factors of active zones of presynaptic membranes].

The differentiation of the subsynaptic areas depends very probably on a local influence exerted by the axon terminals; but conversely, as suggested by obervations on the development of neuromuscular junctions of "fast" and "slow" muscle fibres in Anura, complementing the results of previous degeneration experiments on frog muscles, the subsynaptic areas might intervene in the differentiation of "active zones" of presynaptic membranes.