[Biostructural manifestations of the effect of age on adaptation of neuromotor units upon exposure to measured physical loads].

A quantitative histological investigation of neuromotor units under the effect of skeleteal-muscular loadings with a step-like increase of their volume was performed in white rats of 3 age groups (young, mature and old). It has been stated that hyperfunction of the skeletal muscles produce an increase in the volume of the motoneurons and their structural components (nucleus and nucleolus). Simultaneously, volume and number of perisomatic gliocytes grow larger, as well as the indices on capacity of the hemocapillary bed in the microregion of separate neurocytes increase. Adaptive rearrangement of the functional microcomplex neuron--gliocyte--hemocapillary is accompanied with an increasing area of axomuscular synapses and hypertrophy of the muscular fibres. Degree of vascularization in peripheral parts of the neuromotor units also increases. During some stages of ontogenesis, adaptation of the neuromotor units has its own pecularities. The compensative-adaptive changes are most pronounced in case, if the muscular training coincides with the period of the most intensive growth and maturation of the white rats (30--60 days).