Introduction
The Primary Organs and Structures in the Reproductive System.
- The uterus is a pear-shaped organ located between the bladder and lower intestine. It consists of two parts, the body and the cervix.
- When a woman is not pregnant the body of the uterus is about the size of a fist, with its walls collapsed and flattened against each other. During pregnancy, the walls of the uterus are pushed apart as the fetus grows.
- The cervix is the lower portion of the uterus. It has a canal opening into the vagina with an opening called the os, which allows menstrual blood to flow out of the uterus into the vagina.
- Leading off each side of the body of the uterus are two tubes known as the fallopian tubes. Near the end of each tube is an ovary.
- Ovaries are egg-producing organs that hold 200,000 - 400,000 follicles (from folliculus, meaning "sack" in Latin). These cellular sacks contain the materials needed to produce ripened eggs, or ova.
- The inner lining of the uterus is called the endometrium, and during pregnancy it thickens and becomes enriched with blood vessels to house and support the growing fetus. If pregnancy does not occur, the endometrium is shed and a woman starts her menstrual flow (or "period"). Menstrual flow also consists of blood and mucus from the cervix and vagina.
The uterus is a hollow muscular organ located in the female pelvis between the bladder and rectum. The ovaries produce the eggs that travel through the fallopian tubes. Once the egg has left the ovary it can be fertilized and implant itself in the lining of the uterus. The main function of the uterus is to nourish the developing fetus prior to birth.
Reproductive Hormones. The hypothalamus (an area in the brain) and the pituitary gland control the reproductive hormones. In women, six hormones help regulate the reproductive system:
Click the icon to see an image of the hypothalamus and pituitary gland.
- Gonadotropin-releasing hormone (GnRH) is released by the hypothalamus.
- GnRH stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
- Estrogen, progesterone, and the male hormone testosterone are secreted by the ovaries at the command of FSH and LH.
Click the icon to see an image of the pituitary gland.
Ovulation. The process leading to fertility is very intricate. It depends on the healthy interaction of two sets of organs and hormone systems in both the male and female. In addition, reproduction is limited by the phases of female fertility. Nevertheless, this astonishing process results in conception within a year for about 80% of couples. Only 15% conceive within a month of their first attempts, however, and about 60% succeed after 6 months.
A woman's ability to produce children occurs after she enters puberty and begins to menstruate. The process to conception is complex:
