The ovaries are part of the female reproductive system and are responsible for producing the female gametes or sex cells, known as ova or eggs. Understanding the anatomy and location of the ovaries is important in order to study the process of human reproduction.
Anatomy of human ovaries
The ovaries develop along with other organs in the womb before birth. When a female infant is born, her ovaries will contain approximately 400,000 egg-producing follicles, and for the most part her body will not produce anymore follicles for the rest of her life. During puberty, increasing levels in follicle stimulating hormone (FSH) cause one follicle to release a mature egg in each menstrual cycle; this is the age when females are biologically able to reproduce.
During a woman’s menstrual cycle, the levels of several hormones fluctuate, and ovulation (releasing of a mature egg from the ovary) occurs when levels of luteinizing hormone (LH) peak. If the egg is fertilized by a sperm cell, it will try to implant itself in the thickened lining of the uterus and begin a pregnancy. If the egg is not fertilized, it is released by the body and the uterus will shed its lining (menstruation or period).
Location of the ovaries
Female mammals, including humans, have two ovaries, which are located in the pelvic region. The vagina extends a few centimeters up towards the abdominal cavity until it reaches the cervix, which is the barrier between the vagina and the uterus. The uterus extends up into the lower abdominal cavity approximately 7 cm, narrow at first and gradually widening to approximately 5 cm at the top. From each side of the top of the uterus extends a Fallopian tube, which extends laterally before curving downwards and attaching to the ovary. The ovaries, in turn, are stabilized by a thin fibrous connection with the outside of the uterus.
Journey of an egg from the ovaries
Given the anatomy and location of the ovaries, it is easy to imagine the processes of ovulation and reproduction. When luteinizing hormone levels are high enough to trigger ovulation, one of the ovaries releases an egg from its follicle and it is carried into the Fallopian tube. It stays in the distal part of the Fallopian tube (near the ovary and away from the uterus) until it is either fertilized by a sperm cell or it dies (usually within 12-24 hours). High progesterone levels cause the blood-rich lining of the uterus (endometrium) to thicken in case the egg is fertilized and tries to implant.
If the egg is fertilized and is able to implant in the uterine lining, this begins a pregnancy; the normal ovulation/menstruation cycle is replaced by a gestation (pregnancy) cycle as long as the pregnancy continues. If the egg is not fertilized or if it is unable to implant, it is released by the body during menstruation along with the thickened endometrium, and the cycle begins again.