Dear student,
In menstrual cycle, there are 3 phases- Follicular phase, luteal phase and bleeding phase.
Follicular/Proliferative phase; This phase lasts for about 14 days.During this phase,the primary follicles in the ovary grow to become a fully mature Graafian follicle and the endometrium of uterus regenerates through proliferation.
Because the follicle and endometrium both proliferates in this phase,it is also known as Proliferative phase.
Regards.