What happens during this phase
At the start of the cycle FSH, follicle stimulating hormone, stimulates several follicles in the ovaries to grow. Each follicle contains an immature egg. One follicle becomes dominant and continues to mature. At the same time the uterine lining rebuilds under the influence of estrogen.
The role of estrogen in this phase
As the follicles grow, they produce estrogen. Estrogen levels gradually rise duringthis phase. Estrogen causes the uterine lining to thicken and prepares it forpossible implantation.
Transition to ovulation
When the dominant follicle has matured and estrogen levels are high enough, a rise in LH occurs. This rise leads to ovulation and marks the end of the follicular phase.
Why this phase is important
The follicular phase is the part of the menstrual cycle between menstruation and ovulation. During this time, the egg matures and the uterus is prepared.