What happens to the lining of uterus when follicle changes into a yellow body?

The lining of the uterus, also known as the endometrium, undergoes changes in response to hormonal fluctuations during the menstrual cycle. When a follicle changes into a yellow body (corpus luteum), it signifies that ovulation has occurred. Here's what happens to the uterine lining during this phase:

1. Progesterone Dominance: After ovulation, the corpus luteum produces the hormone progesterone. Progesterone plays a crucial role in preparing the endometrium for the potential implantation of a fertilized egg.

2. Secretory Phase: The phase after ovulation is known as the secretory phase. Under the influence of progesterone, the endometrial lining undergoes further transformation and becomes thick and rich in nutrients to support a potential embryo.

3. Glandular Changes: The glands within the endometrium become more developed and start to secrete a glycogen-rich fluid that nourishes the lining. Additionally, the blood vessels in the lining become more prominent and dilated to increase the blood supply.

4. Cellular Proliferation: The cells of the endometrium proliferate and multiply, further increasing the thickness of the lining. This prepares the uterus to receive and accommodate a fertilized egg if conception occurs.

5. Preparation for Implantation: The changes in the endometrium during the secretory phase create an optimal environment for the implantation of a fertilized egg. If fertilization doesn't occur, the corpus luteum regresses, leading to the breakdown of the endometrium and the onset of menstruation.

In summary, when a follicle changes into a yellow body, the uterine lining undergoes significant changes under the influence of progesterone. It thickens, becomes rich in nutrients and blood supply, and prepares itself for the possible implantation of a fertilized egg. If implantation doesn't occur, the endometrium sheds and menstruation begins, marking the start of a new menstrual cycle.