Eierstockkreislauf

Eierstockkreislauf refers to the cyclical changes that occur within the ovaries of a female mammal during their reproductive years. This process is primarily regulated by hormones and prepares the ovary for potential fertilization and pregnancy. The cycle typically spans around 28 days in humans, though this can vary. It involves two main phases: the follicular phase and the luteal phase.

During the follicular phase, follicle-stimulating hormone (FSH) from the pituitary gland stimulates the growth of several ovarian follicles. Each follicle contains an immature egg. As these follicles grow, they produce estrogen. One dominant follicle typically matures and releases its egg during ovulation.

Ovulation is the release of a mature egg from the dominant follicle, usually occurring around the middle of the cycle. This event is triggered by a surge in luteinizing hormone (LH), also from the pituitary gland. The released egg then enters the fallopian tube, where it can be fertilized by sperm.

Following ovulation, the ruptured follicle transforms into the corpus luteum during the luteal phase. The corpus luteum produces progesterone and some estrogen. These hormones prepare the uterine lining (endometrium) for implantation of a fertilized egg. If fertilization does not occur, the corpus luteum degenerates, leading to a drop in progesterone and estrogen levels. This hormonal decline triggers menstruation, the shedding of the uterine lining, and marks the beginning of a new cycle. If fertilization does occur, the corpus luteum continues to produce hormones to support the pregnancy.