Figure 1 Diagram showing the molecular and biomechanical mechanism of action of osmotic dilators. Swelling of osmotic dilator leads to applying a radial force to the walls of cervical canal. These events lead to mechanical dilation. Mechanical stretching of cervical tissue and surrounding membranes leads to enhanced secretion of IL-1, IL-8, PGs, and HA (which are the main cervical ripening mediators). Increased concentrations of the above substances lead to total rearrangement of the cervical extracellular matrix, thus significantly softening the cervix. PGs – prostaglandins; IL-1 – Interleukin-1; IL-8 – Interleukin-8; HA – hyaluronic acid. Created using MS Word software.