What are the two main phases of the menstrual cycle?

The menstrual cycle is comprised of two main phases: the follicular phase and the luteal phase. During the follicular phase, which begins on the first day of menstruation, the follicles in the ovaries mature under the influence of hormones such as follicle-stimulating hormone (FSH). This phase culminates in ovulation, when a mature egg is released from the ovary.

Following ovulation, the luteal phase takes place. In this phase, the ruptured follicle transforms into the corpus luteum, which produces progesterone, a hormone critical for preparing the endometrium for a potential pregnancy. If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in progesterone levels and the start of menstruation.

Thus, understanding the follicular and luteal phases is crucial as they represent the key physiological changes and hormonal fluctuations that occur throughout the menstrual cycle. The other phases mentioned in the alternatives, such as the ovulatory phase and the menstrual phase, are part of these broader phases but do not encompass the entire cycle as the follicular and luteal phases do.