[The ultrastructure of smooth muscle cells under static stretching].

Smooth muscle cells of the guinea pig vas deferens in the organotypic culture change their phenotype from the contractile to the synthetic one within a month. The activating nucleoli, while increasing the number of free ribosomes and endoplasmic reticulum, decreased the amount of myofilaments and dense bodies. Longitudinal static stretching maintains the contraction phenotype in the longitudinal layer muscle but not in the circular layer.