Monday, 16 February 2015

Female reproductive system

Female reproductive system is located in lower abdomen of women. It`s main function is to incubate the developing fetus and deliver baby into world. It also produces ova (female gamete) every 27-30 days associate with Menstrual cycle and produce couple of female sex  hormones which are required for secondary sexual characters, secretion of milk and pregnancy.The female reproductive organs can be subdivided into the internal and external genitalia .The internal genitalia are those organs that are within the true pelvis. These include the vagina, uterus, cervix, uterine tubes (oviducts or fallopian tubes), and ovaries. The external genitalia lie outside the true pelvis. These include the perineum, mons pubis, clitoris, urethral (urinary) meatus, labia majora and minora, vestibule, greater vestibular (Bartholin) glands, Skene glands, and periurethral area.


External genitalia
The vulva, also known as the pudendum, is a term used to describe those external organs that may be visible in the perineal area (see the images below). The vulva consists of the following organs: mons pubis, labia minora and majora, hymen, clitoris, vestibule, urethra, Skene glands, greater vestibular (Bartholin) glands, and vestibular bulbs.The boundaries include the mons pubis anteriorly, the rectum posteriorly, and the genitocrural folds (thigh folds) laterally.


Mons pubis
The mons pubis is the rounded portion of the vulva where sexual hair development occurs at the time of puberty. This area may be described as directly anterosuperior to the pubic symphysis.

Labia
The labia majora are 2 large, longitudinal folds of adipose and fibrous tissue. They vary in size and distribution from female to female, and the size is dependent upon adipose content. They extend from the mons anteriorly to the perineal body posteriorly. The labia majora have hair follicles.
The labia minora, also known as nymphae, are 2 small cutaneous folds that are found between the labia majora and the introitus or vaginal vestibule. Anteriorly, the labia minora join to form the frenulum of the clitoris.

Hymen
The hymen is a thin membrane found at the entrance to the vaginal orifice. Often, this membrane is perforated before the onset of menstruation, allowing flow of menses. The hymen varies greatly in shape.

Clitoris
The clitoris is an erectile structure found beneath the anterior joining of the labia minora. Its width in an adult female is approximately 1 cm, with an average length of 1.5–2.0 cm. The clitoris is made up of 2 crura, which attach to the periosteum of the ischiopubic rami. It is a very sensitive structure, analogous to the male penis. It is innervated by the dorsal nerve of the clitoris, a terminal branch of the pudendal nerve.

Vestibule and urethra
Between the clitoris and the vaginal introitus (opening) is a triangular area known as the vestibule, which extends to the posterior fourchette. The vestibule is where the urethral (urinary) meatus is found, approximately 1 cm anterior to the vaginal orifice, and it also gives rise to the opening of the Skene glands bilaterally. The urethra is composed of membranous connective tissue and links the urinary bladder to the vestibule externally. A female urethra ranges in length from 3.5 to 5.0 cm.

Skene and Bartholin glands
The Skene glands secrete lubrication at the opening of the urethra. The greater vestibular (Bartholin) glands are also responsible for secreting lubrication to the vagina, with openings just outside the hymen, bilaterally, at the posterior aspect of the vagina. Each gland is small, similar in shape to a kidney bean.

Vestibular bulbs
Finally, the vestibular bulbs are 2 masses of erectile tissue that lie deep to the bulbocavernosus muscles bilaterally.



Internal genitalia
Vagina
The vagina is a canal that joins the cervix (the lower part of uterus) to the outside of the body. It also is known as the birth canal.The vagina extends from the vulva externally to the uterine cervix internally. It is located within the pelvis, anterior to the rectum and posterior to the urinary bladder. The vagina lies at a 90º angle in relation to the uterus. The vagina is held in place by endopelvic fascia and ligaments.
                                                                                                   

Uterus
The uterus is the inverted pear-shaped female reproductive organ that lies in the midline of the body, within the pelvis between the bladder and the rectum. The uterus does not lie in line with the vagina but is usually turned forward (anteverted) to form approximately a right angle with it.It is thick-walled and muscular, with a lining that, during reproductive years, changes in response to hormone stimulation throughout a woman’s monthly cycle.
The uterus can be divided into 2 parts: the most inferior aspect is the cervix, and the bulk of the organ is called the body of the uterus (corpus uteri). Between these 2 is the isthmus, a short area of constriction.
The body of the uterus is globe-shaped and is typically situated in an anteverted position, at a 90º angle to the vagina. The upper aspect of the body is dome-shaped and is called the fundus; it is typically the most muscular part of the uterus. The body of the uterus is responsible for holding a pregnancy, and strong uterine wall contractions help to expel the fetus during labor and delivery. The uterus is composed of three layers of tissue namely outer peritoneum, middle myometrium and innermost endometrium.Endometrium begins to reach full development at puberty and thereafter exhibits dramatic changes during each menstrual cycle

Cervix
The cervix is the inferior portion of the uterus, separating the body of the uterus from the vagina. The cervix is cylindrical in shape, with an endocervical canal located in the midline, allowing passage of semen into the uterus. The external opening into the vagina is termed the external os , and the internal opening into the endometrial cavity is termed the internal os. The internal os is the portion of a female cervix that dilates to allow delivery of the fetus during labor. The average length of the cervix is 3-5 cm.

Fallopian tubes
 Their primary function is to transport sperm toward the egg, which is released by the ovary, and then to allow passage of the fertilized egg back to the uterus for implantation.
The uterine tubes exit the uterus through an area known as the cornua and form a connection between the endometrial and peritoneal cavities. Each tube is approximately 10 cm in length and 1 cm in diameter and is situated within a portion of the broad ligament called the mesosalpinx. The distal portion of the uterine tube ends in an orientation encircling the ovary.

The uterine tube has 3 parts. The first segment, closest to the uterus, is called the isthmus. The second segment is the ampulla, which becomes more dilated in diameter and is the typical place of fertilization. The final segment, furthest from the uterus, is the infundibulum. The infundibulum gives rise to the fimbriae, fingerlike projections that are responsible for catching the egg that is released by the ovary.

Ovaries
The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones. They are about 4 cm (1.6 inches) long, 2 cm  wide, and 1.5 cm (0.6 inch) thick; the two ovaries weigh 4–8 grams . The ovaries are held in place by several ligaments (bands of fibrous connective tissue), including the broad ligament, the suspensory ligament, and the ovarian ligament.The ovaries are responsible for housing and releasing the ova (ovulation), or eggs, necessary for reproduction. At birth, a female has approximately 1-2 million eggs, but only 300 of these eggs ever mature and are released for the purpose of fertilization.  A cross-section of the ovary reveals many cystic structures that vary in size. These structures represent ovarian follicles at different stages of development and degeneration. An ovarian follicle consists of a developing oocyte surrounded by one or more layers of cells called follicular cells.The ovarian follicle with mature oocyte is called Graffian follicle. The Graffian follicle ruptures releasing oocyte and after wards it become a yellow body called Corupus Luteum which secretes Progesterone hormone.

Prepared by Kiran.B




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