A Graafian follicle, also known as a mature follicle, is a fluid-filled structure within the ovary that contains a mature oocyte (egg). It is named after Regnier de Graaf, a Dutch physician who first described it in the 17th century.
The Graafian follicle develops from a small, immature follicle that is present in the ovarian cortex. As the follicle grows, it secretes increasing amounts of estrogen, which causes the lining of the uterus to thicken in preparation for potential pregnancy. The Graafian follicle also produces a fluid that accumulates within the follicle and helps to nourish the oocyte.
When the Graafian follicle is fully mature, it ruptures and releases the oocyte into the fallopian tube, a process known as ovulation. The remaining portion of the Graafian follicle, known as the corpus luteum, begins to produce progesterone to help prepare the uterus for potential pregnancy.
The development of a Graafian follicle is a crucial step in the process of ovulation and female fertility. A failure to develop or release mature follicles can contribute to infertility.