The motor unit: anatomy and histochemical functional correlations.

The glycogen depletion technique has demonstrated the distribution of fibres in normal and reinnervated motor units, the histochemical uniformity of its fibres and enabled direct correlation between histochemistry and function. Homogeneity exhibits the capacity of the motoneurone to determine histochemical and related functional properties of its muscle fibres at a specific level. Changes in rat soleus motor units during growth indicate mechanisms by which the motoneurone is able to alter this level even qualitatively in order to adapt the muscle to its usage.