What occurs during the secretory phase of the menstrual cycle?

• A. The endometrium sheds, resulting in menstruation.
• B. The endometrium thickens and becomes more vascularized to prepare for potential implantation.
• C. The follicular phase begins, leading to the development of ovarian follicles.
• D. Ovulation occurs, releasing an egg from the ovary.

Answer: (B)

Verified step by step guidance

1. Understand that the menstrual cycle is divided into several phases: menstrual, follicular, ovulation, and luteal (secretory) phases.
2. Recognize that the secretory phase occurs after ovulation and is part of the luteal phase, typically lasting from day 15 to day 28 of the cycle.
3. During the secretory phase, the hormone progesterone, secreted by the corpus luteum, plays a crucial role in preparing the endometrium for potential implantation of a fertilized egg.
4. The endometrium thickens and becomes more vascularized, meaning it develops a richer blood supply, to create a supportive environment for a potential embryo.
5. If implantation does not occur, the corpus luteum degenerates, leading to a decrease in progesterone levels, which eventually results in the shedding of the endometrial lining, marking the start of menstruation.