[The formation of motor units in vertebrates (a histophysiological analysis)].

In motor unit anlage successive formation of morphophysiological and biochemical components of system-forming units (histophysiological compartments) occurs. Simultaneously functional differentiation of motor units takes place, based on morphological, biochemical and functional heterogeneity of nervous, muscular and synaptic motor unit components. Intrinsic genetic programmes of main nervous and skeletal muscular tissue differons are the leading ones in early stages of embryogenesis.

[The role of extracellular calcium in regulating the contraction of the developing musculature in the frog Rana temporaria].

Amplitude of both single and tetanic contractile responses of m. gastrocnemius (46th-51st stages of tadpoles Rana temporaria development) in contrast to those of myotomal muscle significantly reduced after decrease of extracellular calcium ion concentration. Such an effect was not observed on later stages.

[Reinnervation of a mixed muscle in the frog Rana temporaria with a regenerating homogeneous nerve].

Mixed muscle m. iliofibularis from the frog Rana temporaria, consisting of monosynaptically innervated phasic and polysynaptically innervated postural muscle fibers, was reinnervated by homogeneous tailor's nerve having no axons of tonic motor system in its composition. Within 2-7 months after nerves binding treatment phasic muscle fibers were easily identified by subneural apparatus structure revealed at coloration of synaptic acetylcholinesterase.

[The interrelationship of the pre- and postsynaptic elements in neuromuscular endings with different functional profiles in the frog Rana temporaria].

Simultaneous investigation of nervous elements and acetylcholinesterase activity in nerve-muscle endings of m. iliofibularis of the frog Rana temporaria revealed different pattern of innervation of muscle fibres of various functional types. Myelinated axons of motoneurones of intermediate muscle fibres, in contrast to phasic ones, do not exhibit preterminal or nodal branching, forming the terminals with relatively rich ramification, but with poor spatial distribution which does not exhibit evident orientation along the muscle fibre.

[The role of axonal transport in regulating the chemosensitivity of muscle spindles in the cat].

The effects of acetylcholine, subecholine and succinylcholine on the afferent activity of the m.EDL muscle spindles were compared before and after suppression of axonal transport by colchicine (20 nM, 30 min). The colchicine increased cholinergic sensitivity of nuclear-bag fibres: i.