What is the Secretory Endometrium?

The secretory endometrium is a phase in the menstrual cycle characterized by high levels of the hormone- progesterone. Progesterone is produced by corpus luteum, which was initially the egg that ruptured having not been fertilized. This phase typically occurs in the second half of the menstrual cycle and is initiated following ovulation and continues until the beginning of the next menstrual period, lasting for about fourteen days. Additionally, during this phase, the uterine glands within the endometrium actively secrete various substances, including glycogen, mucous, proteins, and electrolytes.

Functions of Secretory Endometrium

The secretory endometrium plays several significant roles in the menstrual cycle and female reproductive system. These include:

• Preparation for Embryo Implantation: The secretory endometrium actively secretes substances such as glycogen, mucous, proteins, and electrolytes, which create a nourishing and supportive environment required for successful embryo implantation.
• Hormonal Regulation: The secretory phase is characterized by high levels of progesterone, which is produced by the corpus luteum following ovulation. Progesterone helps in maintaining the endometrial lining and supports early pregnancy.
• Glandular Changes: The secretory endometrium inhabits uterine glands which undergo structural changes, i.e. they become more intricate or curved. These changes improve their ability to secrete secretions that offer nutritional support for a potential embryo.
• Support for Early Pregnancy: To provide support in the initial stages of embryonic development, the secretory endometrium secretes the required substances via the glands present within, along with providing the uterus with enhanced blood flow.
• Menstrual Cycle Regulation: The second half of the menstrual cycle is marked by the secretory endometrium. If the egg does not undergo fertilization, it ruptures ( also known as corpus leteum) and degenerates, while the hormonal levels decrease, causing the secretory endometrium to shed and flow out of the uterus.

The difference between the proliferative endometrium and secretory endometrium is an essential defining factor in menstruation. Understanding these phases is necessary in reproductive physiology and is helpful when evaluating fertility, menstrual irregularities, and certain gynecological disorders. This article discusses the proliferative endometrium and secretory endometrium, the difference between the proliferative endometrium and secretory endometrium, and their respective functions.