The ovaries are the primary sex organs of the female and produce the female sex cells (ovum). They are paired almond-shaped glands, about 3 cm long and 1.5 cm wide and lie close to the lateral pelvic walls.
Each ovary is suspended int he peritoneal cavity by several ligaments. A suspensory ligament holds the upper pole of the ovary to the pelvic wall and an ovarian ligament holds the lower pole to the uterus. The frontal border of the ovary is attached to the back of the broad ligament by a fold of peritoneum called the mesovarium. Its medial surface is covered by the uterine tube, which arches over the ovary to end in finger-like fimbriae and cover its lateral surface.
At birth each ovary contains a large number of primary oocytes. Each primary oocyte is enclosed in a primordial follicle and after puberty, just before the beginning of each menstrual cycle some of the primordial follicles develop into graafian follicles. One of these graafian follicles will continue to mature and rupture, allowing an ovum (oocyte) to leave the ovary. The ovum then travels down the uterine tube where it may be fertilized by a male sperm.
After the ovum has been released into the uterine tube the remains of the graafian follicle in the ovary develops into a corpus luteum. The corpus luteum releases progesterone and oestrogen, which triggers the endometrial lining of the uterus to thicken, ready to receive the egg. If the ovum is fertilized, the corpus luteum will remain until after the pregnancy, otherwise it will degenerate within two weeks. If the ovum is not fertilized and the hormones are no longer released, the endometrium is shed in a process called menstruation.
The function of the ovary is controlled by the follicle stimulating hormone (FSH) and luteinizing hormone, released from the anterior pituitary gland. The hormones are also responsible for the development of secondary sexual characteristics, which include growth of the breasts and pubic hair.
At the age of about 45, the ovaries stop producing ova in a process called the menopause.
The paired uterine tubes receive the oocyte from the ovary and provide a site for fertilization. After fertilization the resulting zygote is conveyed along the rest of the tube to the uterus by the movement of cilia lining the tube.
Each uterine tube is around 10 cm in length and can be divided into 4 parts;
The uterus is a hollow organ with thick muscular walls approximately 8 cm long, 6 cm wide, and 3 cm thick. It is roughly pear-shaped and usually lies at right angles to the vagina in between the rectum and the bladder.
It can be described in three parts;
The walls of the uterus are composed of three layers;
The uterus is held in position by a series of ligaments;
If an oocyte is successfully fertilized in the uterine tube, it travels to the cavity of the uterus and becomes embedded within the endometrium of the uterine wall. Here the developing foetus grows until it fills the uterus, from which point the uterus will expand with it. Where the egg implants will determine the site of the placenta, an organ that supplies the foetus with maternal blood.
Menstruation is the shedding of the endometrial lining of the uterus. This occurs every month in women from puberty to the menopause. The following table describes how hormones control this process;
The vagina is a fibromuscular tube that runs between the cervix and the vaginal orifice. It lies anterior to the anal canal and rectum, and posterior to the bladder and urethra, which is embedded within its anterior aspect. The vaginal walls consist of an outer connective tissue layer, a middle muscular layer and an inner mucosa. The muscular layers of the vaginal walls are composed of smooth muscle arranged in an external longitudinal and an internal circular layer. The vagina is lubricated by mucous glands found on the cervix as well as the secretions of the greater vestibular glands..
It serves as the outlet for menstrual flow, receives the erect penis during intercourse, and forms the inferior portion of the birth canal in parturition.
The external genitalia of the female are collectively known as the vulva, and are described as the following structures;
The breasts are accessory organs to the female reproductive system. They are mounds of a variable size and shape that lie on the front of the thorax superficial to pectoralis major. The breasts develop during puberty and then again during pregnancy. In the centre of each breast is the nipple, which turns from pink to brown after a woman has her first child.
Each breast contains mammary glands that form 15 to 20 lobes and are arranged like the petals of a flower. Each lobe has many smaller lobules, which end in dozens of tiny bulbs that can produce milk. Ducts drain the milk from these lobes into the centre of the nipple, the areola. The breasts will secrete an antibody-rich substance called colostrum for about three days after childbirth, after this they produce milk.