The Female Ovaries

Abstract Each ovary is a small glandular organ about the shape and size of an almond. The ovaries are located on opposite sides of the uterus in the pelvic cavity and are attached to the uterus by the ovarian ligaments, the ovaries are the most important organs of the female reproductive system. Their importance is derived from their role in producing both the female sex hormones that controls reproduction and the female gametes that are fertilized to form embryos.

The ovaries are filled with follicles. Follicles are fluid-filled structures in which the oocyte, also called egg grows to maturity. Current knowledge indicates that females are born with their entire lifetime supply of gametes. At birth, the normal female ovary contains about 1-2 million oocytes eggs. Females are not capable of making new eggs, and in fact, there is a continuous decline in the total number of eggs each month. By the time a girl enters puberty, only about 25 percent of her lifetime total egg pool remains, around 300,000. Over the next 30-40 years of a female's reproductive life, the entire egg supply will be depleted. Although no one can know with absolute certainty the number of eggs remaining within the ovaries at any given time, most women begin to experience a significant decrease in fertility, the ability to conceive a child around the age of 37. At the time of menopause, virtually no eggs remain. The maturation of eggs typically takes about 14 days and can be divided into 2 distinct periods. During the initial period, many eggs, as many as 1000, begin to develop and mature.
The second phase of development requires gonadal hormone stimulation to stimulate further development. However, even though hundreds of eggs have begun to mature, most often only one egg will become dominant during each menstrual cycle, and reach its' fully mature state, capable of ovulation and fertilization. The remaining eggs follicles will wither and die. The large number of eggs that are used each month account for the steady decline in the female's total egg pool that occurs from birth to menopause. Once the egg is released from the ovary, it travels for several days through the oviduct to reach the uterus. The fallopian tube helps in movement of the eggs by carrying out wavelike movements. The fallopian tubes are lined with cilia internally. They help in pushing the sperm towards the egg. The egg is fertilized within the fallopian tube near the ovary. After about 5 to 6 days, the fertilized egg will reach the uterus. There is one more function of the ovaries that involves hormonal regulation. Let us have a look at their function related to hormones. Estrogen and progesterone are the two hormones secreted by the ovaries. Estrogen is the hormone that helps in exhibition of the secondary sexual characteristics of females during puberty. It is also responsible for the maturation as well as the maintenance of the reproductive organs once they reach their mature functional role. Progesterone also works with estrogen in carrying out the cyclic changes of the endometrium. This means it prepares the endometrium for pregnancy and also maintaining the health of the endometrium during the period of pregnancy. After menopause, a woman's ovaries are no longer producing estrogen, at least not