Female reproductive system. - Biology Of Things

Female reproductive system - An easy understanding.

The female reproductive system is far more complex than the male because in addition to gamete formation, it has to nurture the developing foetus.

It consists of:

1)      Pair of ovaries,

2)      Accessory organs,

1.       The fallopian tubes,

2.       Uterus,
       a)    Fundus,
       b)    Body,
       c)     Cervix.

3.        Vagina,

      3)      The external genitalia.

1.       Mons Pubis,

2.       Labia Majora,

3.       Labia Minora,

4.       Clitoris,

5.       Hymen,

6.       Bartholin’s glands,

7.       Skene’s glands.

These parts along with the mammary glands are integrated structurally and functionally to support the,

• Process of ovulation,
• Fertilisation,
• Pregnancy,
• Child birth, and
• Child care.

Female pelvis shows reproductive system.

1)   Pair of Ovaries:

Cross sectional view of ovary with inner markings.

Function: As primary female sex organs, producing female gamete known as ovum.

Location: One on each side of lower abdomen (Abdominal cavity). Alongside the lateral wall of uterus in a region called ovarian fossa.

Structure: Elliptical.

Size: 2-4 cm long.

Shape: Almond shape.

Color: whitish.

Ovaries covered by: A thin cuboidal epithelium called germinal epithelium which encloses the ovarian stroma. Below the germinal epithelium there is a presence of a dense connective protective tissue called Tunica albuginea.

Ovarian stroma:

Cross sectional view of ovarian stroma.

• It is connective tissue, abundantly supplied with blood vessels. It also contains ordinary connective tissue such as reticular fibres and collagens.
• The entire stroma is highly vascularised.
• It is highly condensed on its surface to form a layer (tunica albuginea) composed of short connective-tissue fibres, with fusiform cells between them.  
• The ovarian stroma may contain interstitial cells resembling those of testis.

Ovarian stroma.

• Ovarian stroma is differentiated into outer cortex and inner medulla.

Outer cortex:

• It is dense and glandular due to presence of ovarian follicles in different stages of development.

Inner medulla:

• It is a loose connective tissue.
• It contains abundant blood vessels, lymphatic vessels, nerve fibres, collagen fibres.

Cross sectional view of inner medulla and cortex of ovary.

Attachment of ovary: To the pelvic wall and the uterus by an ovarian ligament called mesovarium.

Function of mesovarium:

• It keeps the ovary in position.
• Acts as protective covering for it.

Posterior view of female reproductive system.

2)  Accessory organs:

consists of:

      1)      The fallopian tubes (uterine tubes or oviducts), 

      2)      Uterus,

      3)      Vagina.
                              

         

Female reproductive system.

1.   Fallopian tubes (Salpinges):

Location: In the female abdominal cavity. It extends from periphery of each ovary to uterus.

Structure: Pair of long, narrow ducts.

Function:

• Transportation of male sperm cells to the egg.
• Provides suitable environment for fertilization.
• Transports fertilized egg (embryo) into the uterine wall from ovary.

Fallopian tube of ovary.

Size:

• 10-13 cm (4-5 inches) long.
• 0.5-1.2 cm (0.2-0.6 inch) in diameter.

Fallopian tube consists of:

1. Infundibulum,
2. Ampulla,
3. Isthmus.

Infundibulum:

Shape: funnel shape.

The edges of infundibulum have finger like projections called fimbriae (helps in collection of ova after ovulation).

Location: Proximal part of the fallopian tube.

Ampulla:

• Located next to infundibulum.
• It is wider central portion.

Isthmus:

• It is the last part of the oviduct

Structure: It is short and thick-walled structure.

Function: connects ampulla and infundibulum to uterus.

Size: 2 cm (0.8 inch) long.

2.   Uterus (womb):

• It is hollow,
• Thick walled,
• Muscular,
• Highly vascular,
• Inverted peer shaped structure.
• It is the secondary sex organ,
• It provides mechanical support, nutritional support and waste removal for the developing embryo (weeks 1-8) and foetus (from week 9 until delivery).
• Responsible for the maintenance and transportation of the gametes,
• It has the capability to accommodate a growing foetus.

Location: Between urinary bladder and rectum, lying in pelvic cavity.

Uterus portion is covered by: 

a)   Fundus,

It is the top rounded portion of the uterus, above the entry point of the uterine tubes.

b)   Body:

It is the usual site for implantation of the blastocyst.

c) Cervix:

• The uterus opens into the vagina through a narrow cervix.
• It is the lower part of the uterus. It is cylindrical or conical in shape.
• This part is structurally and functionally different to the rest of uterus.
• The cavity of the cervix is called the cervical canal.
• The cervical canal communicates with the vagina through external orifice and with uterus through internal orifice.
• The cervical canal along with the vagina forms the birth canal.

The wall of uterus consists of:

Perimetrium:

• It is the outermost thin membranous serous layer.

Myometrium:

• It is the thick muscular middle layer.
• It exhibits strong contractions during parturition.

Endometrium:

• It is the inner glandular layer.
• It undergoes cyclic changes during menstrual cycle.

Facts of uterus:

• The female uterus contains one of the strongest muscles of human body.
• The female uterus is normally about 3 inches long and 2 inches wide but can expand 20 times during pregnancy.

3.   Vagina.

• It is the large fibromuscular tube.
• It extends from cervix to the exterior.
• It accommodates the male penis during sexual intercourse.

Function: For copulation.

3) External genitalia or vulva:

The female reproductive structure that lie external to the vagina are called as the external genitalia.

The external genitalia comprising of:

1. Mons pubis,
2. Labia majora,
3. Labia minora,
4. Hymen,
5. Clitoris,
6. Bartholin’s glands, and
7. Skene’s glands.

Vulva of female reproductive system.

 1.    Mons pubis:

Structure: Inverted triangular area of fatty tissue. Extends from the pubic hairline. It is a fatty tissue, lies over the pubic symphysis.

Covered by: Hair follicles on the top of pubic bone.

2.    Labia majora:

• They are fleshy folds of tissue also known as “Major lips” or “Large lips”.
• They are homologous to scrotum in males (it is derived embryologically from the same tissue).

Location: It extends down from mons pubis and surround the vaginal and urethral orifices.

It composed of: Subcutaneous adipose tissue and fat.

Function: It encloses and protects other external reproductive organs.

It contains:

• Sweat and oil secreting glands,
• Fat,
• Pubic hair follicles, and
• Fewer touch and pressure receptors. In the surface the skin it contains squamous epithelium.

3.    Labia minora:

•  Also known as “Minor lips” or “Small lips”.

Structure: Two small cutaneous, smooth paired folds.

Size: 3-4 cm long, 2 inches wide approximately.

Location: Underlying the labia majora, it extends anteriorly from clitoris to the fourchette (a small fold of membrane connects labia minora in the posterior part of vulva) posteriorly.

Labia minora contains: Rich in sebaceous glands, connective tissues and vascular erectile tissue, with a considerable number of sensory nerve endings and receptors.

Color: Ranging from light pink to brownish black in colour in different individuals.

4.    Clitoris:

• It is an erectile structure.
• It is homologous to male penis.

Location: Lies at the anterior junction of the two labia minora, above the urethral orifice and at the lower border of the pubic bone.

Clitoris formed by: Two corpora cavernosa and the glans, formed by prepuce. It is rich in sensory receptors.

Visible portion: only a fifth (or less portion) is visible (glans) while the rest is hidden under the skin. The glans is the externally visible portion of the clitoris.

Size: Average length is about 1-1.5 cm (0.5 inch) and 0.5 cm in diameter. There is however, considerable variation in clitoral size.

Clitoris glans covered by: Partially by clitoral prepuce, which is homologous to a similar structure covering the glans of the penis.

5.    Hymen:

• It is a thin ring of tissue.
• It is a septum of mucous membrane, which varies in shape greatly.
• It is usually crescentic or circular in virgins and is ruptured during sexual intercourse.
• It forms the part of vulva.
• Hymen is rich in nerve endings.

Variation: It ranges from thin to thick, stretchy and may be rigid, may also be completely absent. An imperforate hymen occurs in 1-2 out of 1000 infants.

Appearance: Normal appearance of hymen is crescent shaped, although many shapes are possible. Due to secretion of oestrogen hormone in puberty it become elastic and change in appearance.

Function: The external opening of the vagina is partially closed by this hymen. The hymen is often torn during the first coitus (physical union). It may also remain intact in some women. It can be torn or stretched due to a sudden fall or jolt and also during strenuous physical activities such as horseback riding, cycling, etc., and therefore cannot be considered as an indicator of a woman’s virginity.

6.    The Bartholin’s glands (the Greater vestibular glands):

Location: Posterior to right and left openings vagina.

Secretion: Mucous.

Function: To lubricate the vagina and are homologous to bulbourethral glands of male.

Image shows Bartholin's glands.

7.    Skene’s glands:

Location: On the anterior wall of vagina and around the lower end of the urethra.

Contains: Numerous microanatomical structures in common with prostate glands such as secretory cells.

Secretion: A lubricating fluid, homologous to the prostate gland of males.

Image showing Skene's glands.

Mammary glands:

• These glands are present in both males and females.
• They are modified sweat glands.
• It is rudimentary in males and functional in females.

Location: A pair of mammary glands is located in the thoracic region.

It contains variable quantities of fat with a median nipple and a glandular tissue.

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The nipple is surrounded by a pigmented area called the areola. Areolar glands or sebaceous glands found on the skin to reduce the cracking of the skin of the nipple.

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Each mammary gland consists of 2-25 lobes, and they are separated by connective tissues and fats. Each lobe is made up of lobules.

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Lobules of each lobe contains alveoli or acini lined by epithelial cells.

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The cells of alveoli secrete milk.

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The alveoli open into mammary tubules.

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The tubules of each lobe join to form a mammary duct.

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Several mammary ducts join to form a wider mammary ampulla.

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The ampulla is connected to the lactiferous duct in the nipple.

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Under the nipple, each lactiferous duct expands to form the lactiferous sinus.

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The lactiferous sinus serves as a reservoir of milk.

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Each lactiferous duct opens separately by a minute pore on the surface of the nipple.

The normal development of breast begins at puberty and progress with changes during each menstrual cycle. The glandular structure in non-pregnant women is largely underdeveloped and the breast size is largely due to amount of fat deposits. The size of breast does not have an influence on the efficiency of lactation.

Mammary glands-cross sectional view.

More to know:

1. Male reproductive system

2. What is Aquaponics.