A fluid-filled space (like a balloon) present inside the ovary that contains and nourishes the egg. In a normal cycle, a woman will usually ovulate only one egg. Very early in the cycle, however (and actually before the cycle even begins), many small minute follicles containing immature eggs are recruited. During the first 5 to 7 days after the start of a period only one of these follicles will mature and grow. This leading follicle will increase and be ready for ovulation roughly 2 weeks after the start of the menstrual cycle. The follicle will then burst with ovulation and release the egg that is picked up by the finger-like projections (fimbria) of the fallopian tube. The collapsed follicle will become the corpus luteum.