The Vagina: Orgasmic Platform
During this phase, there is only a slight increase in length and width of the inner two thirds of the vagina. However, its outer one third becomes congested with blood. As a result, this part of the vagina, which might have widened somewhat during the excitement phase, now narrows by about 33 percent. This congested and tightening outer third of the vagina has been named the''orgasmic platform" by Masters and Johnson.

The Major and Minor Lips
While the major lips show no further changes during the plateau phase, the minor lips continue to darken in color, especially in women who have given birth. This marked color change is a sign that orgasm is approaching.