Understanding the Menstrual Cycle: Follicular and Luteal Phases

Understanding Reproduction: A Closer Look at the Menstrual Cycle

Reproduction is a fundamental biological process that allows species to perpetuate themselves through sexual reproduction. In mammals like humans, this process involves several complex steps, including the menstrual cycle, which plays a crucial role in preparing the female reproductive system for pregnancy.

The Menstrual Cycle Explained

The menstrual cycle can be divided into two main phases—the follicular phase and the luteal phase:

1. Follicular Phase (Days 1–14): This phase begins with the shedding of the uterine lining during menstruation and continues until ovulation occurs. During this time, the ovaries produce hormones that help prepare the reproductive tract for potential fertilization.

   • Day 1 marks the first day of menstruation, when the uterus sheds its lining due to hormonal changes.
   • Oestrogen levels increase, causing thickening of the uterine lining (endometrium) to support a possible embryo if fertilization occurs.
   • Levels of progesterone remain low during most of the follicular phase.

2. Luteal Phase (Day 15–28): After ovulation, the corpus luteum produces progesterone to maintain the uterine lining. If fertilization does not occur within 24 hours after ovulation, the corpus luteum starts to degenerate, leading to the decline in progesterone production.

   • Progesterone levels rise significantly post-ovulation, maintaining the endometrium's thickness for an implanting embryo.
   • If fertilization does not happen, the corpus luteum breaks down, leading to decreased production of progesterone and subsequent menstruation.

In summary, the menstrual cycle involves the coordinated action of various hormones, such as oestrogen and progesterone, to ensure the health and preparation of the reproductive system for potential conception.