Definition of Endometrium
The endometrium is a layer of tissue that lines the innermost part of the uterus, known as the womb, in females. It plays a crucial role in the menstrual cycle and pregnancy.
Structure
The endometrium consists of two main layers:
- Functional layer: Also known as the stratum functionalis, this layer thickens and sheds during the menstrual cycle in preparation for embryo implantation. If fertilization does not occur, this layer is shed during menstruation.
- Basal layer: Also known as the stratum basalis, this layer remains relatively unchanged and serves as the source of new endometrium after menstruation.
Function
The endometrium is involved in several crucial functions:
- Menstruation: During each menstrual cycle, the functional layer of the endometrium is shed, resulting in menstrual bleeding.
- Embryo implantation: If a fertilized egg implants into the endometrial lining, it forms a connection with the maternal blood supply, allowing for the growth and development of the embryo.
- Supporting pregnancy: Once implantation occurs, the endometrium continues to grow and support the developing embryo, providing it with essential nutrients and oxygen.
Regulation
The endometrium is regulated by hormonal changes throughout the menstrual cycle:
- Estrogen: During the follicular phase of the menstrual cycle, estrogen levels rise, causing the endometrium to thicken.
- Progesterone: After ovulation, the corpus luteum produces progesterone, which further thickens the endometrium and prepares it for potential embryo implantation.
- Menstruation: If fertilization does not occur, estrogen and progesterone levels drop, leading to the shedding of the functional layer of the endometrium.
In summary, the endometrium is a vital tissue lining the uterus that undergoes cyclic changes during the menstrual cycle to support embryo implantation and pregnancy.