Menstrual Cycle Basics

Role of Estrogen in the Menstrual Cycle

• Estrogen regulates the menstrual cycle and influences the development of the endometrial lining.
• Peak levels of estrogen trigger the luteinizing hormone surge, leading to ovulation.
• Contributes to secondary sexual characteristics and reproductive function.

Ovarian Cycle Composition

• The ovarian cycle comprises three phases: follicular phase, ovulation, and luteal phase.
• The follicular phase involves the maturation of ovarian follicles stimulated by hormones.
• Ovulation marks the release of a mature egg from the dominant follicle.
• The luteal phase occurs after ovulation, during which the corpus luteum forms and produces hormones.

Oocyte Production and Growth

• The production and growth of oocytes are prompted by gonadotropins, specifically follicle-stimulating hormone (FSH).
• FSH stimulates the growth of ovarian follicles, leading to oocyte maturation.
• Hormonal feedback loops regulate this process, ensuring proper timing during the menstrual cycle.

Uterine Cycle Responsibility

• The uterine cycle prepares the endometrium for potential implantation of a fertilized egg.
• It consists of the menstrual phase, proliferative phase, and secretory phase.
• Hormonal changes throughout the cycle synchronize the endometrial development with ovarian function.

Menstruation Significance

• Menstruation is a sign of the shedding of the endometrial lining when fertilization does not occur.
• It typically indicates the end of one menstrual cycle and the beginning of another.
• Menstrual flow is composed of blood, tissue, and mucus discharged from the uterus.

Phases of the Uterine Cycle

• The uterine cycle is divided into three main phases:
  • Menstrual Phase: Shedding of the endometrial lining.
  • Proliferative Phase: Regrowth of the endometrium under estrogen influence.
  • Secretory Phase: Further thickening of the endometrium, preparing for potential embryo implantation.

Test your knowledge of the natural changes in hormone production and the structures of the uterus and ovaries in the menstrual cycle. Learn about the ovarian and uterine cycles and how they work together to make pregnancy possible.