Endometrial lining

Endometrial Lining

The endometrial lining, also known as the endometrium, is the innermost layer of the uterus. It plays a crucial role in the reproductive system of female mammals, including humans. The endometrium undergoes cyclical changes in response to hormones, which are part of the menstrual cycle. These changes prepare the endometrium for potential pregnancy and are divided into two main phases: the proliferative phase and the secretory phase.

Structure and Function

The endometrium consists of a single layer of columnar epithelium plus the stroma on which it rests. It is rich in blood vessels, glands, and immune cells. The primary function of the endometrial lining is to provide a suitable environment for the implantation and nourishment of a fertilized ovum (egg), leading to successful pregnancy. If implantation does not occur, the endometrium is shed during menstruation.

Proliferative Phase

The proliferative phase is the first phase of the endometrial cycle and occurs after menstruation. It is characterized by the rebuilding of the endometrium that was shed during the previous cycle. This phase is under the control of estrogen, which is produced by the ovaries. Estrogen stimulates the cells of the endometrium to grow and proliferate, preparing the uterus for potential pregnancy.

Secretory Phase

Following ovulation, the endometrium enters the secretory phase. This phase is dominated by the hormone progesterone, which is produced by the corpus luteum in the ovary. Progesterone causes the endometrium to become more glandular and vascular, creating an environment suitable for the implantation of a fertilized egg. If fertilization does not occur, progesterone levels fall, leading to menstruation.

Clinical Significance

The endometrial lining is central to several clinical conditions, including endometriosis, endometrial cancer, and infertility. Endometriosis occurs when endometrial-like tissue grows outside the uterus, causing pain and potentially affecting fertility. Endometrial cancer is a type of cancer that starts in the cells of the endometrium. It is often detected early because it frequently produces abnormal vaginal bleeding, increasing the chances for successful treatment. Infertility can sometimes be linked to issues with the endometrium, such as inadequate thickness, which can prevent implantation.

Diagnosis and Treatment

Diagnosis of endometrial conditions may involve ultrasound, hysteroscopy, or endometrial biopsy. Treatment varies depending on the condition but may include hormonal therapies, surgery, or in the case of infertility, assisted reproductive technologies (ART) like in vitro fertilization (IVF).

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