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Female Reproductive System

November 12, 2010

Ovaries

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.

Ovulation

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 OVARY

The ovary labeled

Uterine tubes

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;

Name Description
Infundibulum The wide, funnel-shaped, distal end of the uterine tube that is closely associated with the ovary. It has finger-like processes or fimbriae, that loosely enclose the ovary.
Ampulla The middle and longest part of the uterine tube. It is within the lumen of the ampulla that fertilization generally occurs.
Isthmus The medial third of the uterine tube, it is the narrowest part of the tube and opens into the upper end of the uterus.
Intrauterine part The part of the tube which passes through the wall of the uterus to open into the uterine cavity through the small uterine os.

Uterus

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;

Name Description
Cervix The narrow neck of the uterus that protrudes into the vagina inferiorly. It has a narrow canal running through it, connecting the cavity of the uterus to that of the vagina. The upper opening is called the internal os, and the lower opening the external os.
Fundus The dome-shaped portion that lies superior to the entry point of the uterine tubes.
Body The main, pear-shaped part of uterus.

THE UTERUS

The uterus labeled

The walls of the uterus are composed of three layers;

Name Description
Perimetrium The outer layer of connective tissue, derived from peritoneum.
Myometrium The middle layer of smooth muscle, which contracts rhythmically during childbirth to expel the baby.
Endometrium The internal mucosal layer that thickens during the menstrual cycle and partially disintegrates prior to menstruation.

The uterus is held in position by a series of ligaments;

Name Description
Broad ligament A sheet of peritoneum that suspends the uterus from the lateral pelvic walls.
Round ligament Lies within the broad ligament and travels out of the pelvic cavity through the inguinal canal to the labia majora. They are homologous with the ductus deferens in the male.
Transverse cervical ligament Runs in the broad ligament to hold the cervix to the lateral cervical wall.
Uterosacral ligament Connects the cervix to the sacrum.

Source: Anatomy.tv/StudyGuides

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