Formation of the nemaline structures in soleus muscle of rats subjected to long-lasting immobilization.

We performed the ultrastructural evaluation of presence and of some basic morphometric parameters of nemaline structures (NS) and Z band malformations in the musculus soleus fibres of rats kept in 7 months lasting immobilisation. Disturbances in Z band, leading to NS formation, were observed very often. Also numerous, classically rod-shaped NS were found in analyzed material. We demonstrate, for the first time in literature, that long-lasting hypokinesia induces NS formation. The pictures obtained may suggest successive steps in NS formation and maturation.