[The ultrastructure of the neuromuscular synaptic terminal in the frog after denervation].

Ultrastructure of certain myoneural terminals were studied on serial sections on day 3, 5 and 8 after denervation. Ultrastructure of the terminal proximal and distal regions and Schwann cell were studied by means of morphometry and reconstruction of single terminals. On day 3 after denervation Schwann cell is activated in terminal proximal regions more rapidly than in distal ones with contractility in the terminal proximal region being more significant than in distal.

[The ultrastructure of the neuromuscular synapses at different stages in the development of the embryos and tadpoles of the clawed toad].

Myoneural synapses were studied in embryos and tadpole of Xenopus laevis on different stages of development using light and electron microscopy. On embryonal stages, during hatching and on stages of tadpole myoneural synapses vary in in appearance, number of organelles and extent of formation of different synaptic specialisations. During the process of myoneural contacts forming in the development of amphibians, terminal is the first to form, followed by the Schwann cell, that covers it, and postsynaptic plication forms in the last turn.

[The ultrastructure of the individual nerve endings of the tonic fibers in the frog].

A regular diminution of specific areas of synaptic contacts and active zones (AZs) along the terminals towards the distal parts has been first shown. The discontinuity was found in the terminal nerve branch apposition to the muscle fiber as a result of periodic intercalation of the Schwann cell and its processes into the synaptic gap. A significant variability in shapes of active zones lengthways the terminal is revealed.

[Nonuniformity of the fine structure of various portions of the nerve terminal in frog somatic muscles as the basis for the variation in its efficiency].

The ultrastructure of serially sectioned single terminals of two neuromuscular synapses differing in efficacy in frog sartorius and cutaneous pectoris muscles was investigated. Their central (CP) and distal (DP) parts were studied morphometrically, and the data on the terminal ultrastructure in different muscles were compared. The areas of active zones (AZ) in CP of terminals in both the muscles were significantly larger than in DP.