CHAPTER 6

FEMALE REPRODUCTIVE SYSTEM

INTRODUCTION

The female reproductive system is a complex and essential system that plays a critical role in the development of the female body and the continuation of the human species.

The female reproductive organs are those concerned with producing, transporting and nourishing the female gametes, copulation, fertilization, growth and development of the fetus and its subsequent exit into the outside world. The organs are broadly divided into:

• External genitalia

• Internal genitalia

• Accessory reproductive organs

Coronal section of a female reproductive organ

EXTERNAL GENITALIA

The external genitalia, also known as the vulva, are the visible parts of the female reproductive system that are located outside the body.

This includes the:

• mons pubis
• labia majora
• labia minora
• hymen
• clitoris

• vestibule
• urethra
• skene’s gland
• Bartholin glands
• vestibular bulbs

All of these structures work together to facilitate sexual arousal, intercourse, and reproduction in females.

The vulva

Mons Pubis

Also known as mons veneris, is a round pad of subcutaneous fatty connective tissue located over the symphysis pubis. It is typically covered with pubic hair after puberty and serves as a protective cushion during sexual activity.

Labia Majora

• Also known as greater lip.
• The vulva is bounded on each side by the elevation of the skin and subcutaneous tissue which form the labia majora. The skin folds are continuous where they join medially to form the posterior commissure in front of the anus. The outer skin fold surface has hair follicles whereas the inner skin fold lacks hair follicle but is rich in sebaceous glands.
• There are certain specialized sweat glands called apocrine glands, which produce a characteristic aroma.

Labia Minora

• Also known as lesser lip. They are two thin folds lying within the labia majora.
• Labia minora is devoid of fat and pubic hair, but rich in sudoriferous gland. Anteriorly they divide to enclose the clitoris. The frenulum is formed by the two medial parts, posteriorly they fuse to form the fourchette.
• Between the fourchette and the vaginal orifice is the fossa navicularis. The labia minora are homologous to the penile urethra and part of the skin of the penis in males.

Clitoris

It is a small cylindrical erectile, highly sensitive and erogenous organ, situated in the most anterior part of the vulva between the labia minora. It consists of glans, a body and two crura. The clitoris is measured about 1.5- 2 cm long and 5 mm wide. A clitoris of more than 3.5 cm in length and 1 cm in width is called clitoromegaly and occurs in virilism due to excess of androgen hormone.

Vestibule

It is of triangular space that is anteriorly bounded by the clitoris, posteriorly by the fourchette, and on either side by labia minora. The vestibule consists of four openings-

• urethral opening
• vaginal orifice and hymen
• the opening of Bartholin’s ducts
• skene’s glands

• Urethral opening: It is also known as external urethral orifice, is the opening in the front of the vulva, located 2-3 cm below the clitoris and just above the vaginal opening.
• Vaginal orifice: It is also known as the introitus of the vagina, an opening of the vagina to the exterior, occupies 2/3 of the vestibule. The orifice is partially closed by the hymen, a thin membrane that tears during sexual intercourse or during the birth of the first child.

• Bartholin’s ducts: Bartholin glands are two small pea-sized glands open on either side of the vaginal orifice and lie in the posterior part of the labia majora (Fig. 3). These glands secrete alkaline mucous secretions which lubricate the vagina during excitement. Bartholin’s glands are homologous to the bulb of the penis in males.
• Skene’s glands: These are the glands present on either side of the external urethral orifice. They are also known as paraurethral glands and are homologous to the prostate in the males.

Perineum of female

Blood Supply of External Genitalia

• Arteries: Branches of pudendal arteries and the branches of the femoral artery.
• Veins: Veins form plexuses and drain into internal pudendal vein, vaginal venous plexus, long saphenous vein.
• Lymphatic drainage: It is mainly via the inguinal glands.
• Nerve supply: It is derived from branches of the pudendal nerve.

Homologous organs

INTERNAL GENITAL ORGANS

The internal organs in females include the

• vagina
• uterus
• fallopian tubes
• ovaries

These organs are placed internally and require special instruments for inspection.

Structure of vagina

Vagina

The vagina is a hollow distensible fibromuscular tube that extends from the vaginal orifice to the uterine cavity. It measures about 10 cm or 4 inches long with a diameter of 2.5 cm. When a woman gives birth and during sexual intercourse, the vagina temporarily widens and lengthens. In an upright position, the canal is directed upwards and backward forming an angle of 45° with the uterus

Functions of Vagina

• It is an organ of copulation.

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• It allows the escape of the menstrual fluids.

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• It provides an exit for the fetus during birth

Layers

• Mucosal layer is the innermost layer of the vagina, lined by stratified squamous epithelium without any secreting glands.
• Muscularis layer is composed of an outer longitudinal and inner circular muscles.
• Adventitia layer is the outermost layer of the vagina, consisting of areolar connective tissue.

Uterus

• The uterus is a hollow pyriform muscular organ situated in the true pelvis between the bladder (in front) and the rectum (behind).
• In a nulliparae female, the uterus size is small as about 7.5 cm long, 5 cm wide and 2.5 cm deep and 1.25 cm thick as compared to a pregnant female.
• A non-pregnant uterus weighs 50-80 grams.
• Two normal positions of the uterus are:

1.Anteversion: The uterus is leaned forward.

2.Anteflexion: The uterus bends forward upon itself.

Functions

• Uterus serves as a pathway for sperm deposition in the vagina to reach the fallopian tubes.

• It is also the site of implantation of a fertilized ovum, development of the fetus during pregnancy, and labor.

• During reproductive cycles when implantation doesn’t occur, the uterus is the source of menstrual flow.

Structure of uterus and ovaries

Structure

The uterus is divided into :

• Body or corpus
• Isthmus
• Cervix

Layers

• Perimetrium
• Myometrium
• Endometrium

The endometrium is divided into two layers:

1. The stratum functionalis

2. The stratum basalis

Blood Supply

• Arteries: Branches of the internal iliac artery called uterine arteries supply blood to the uterus.
• Straight arterioles supply the stratum basalis with the material needed to regenerate the stratum functionalis.
• Veins: blood is drained by the uterine veins into the internal iliac veins.
• Lymphatic drainage: Lymph drains from the uterine body to the internal iliac glands and from the cervical area to many other pelvic lymph glands.
• Nerve supply: the nerve supply is mainly from the autonomic nervous system, sympathetic and parasympathetic, via the inferior hypogastric or pelvic plexus.

Fallopian Tubes

• Fallopian tubes are also known as uterine tubes, oviducts, and salpinges.
• Females have a pair of tubes, measure about 10 cm, connecting the ovaries with the uterus.

Parts

From medial to lateral

• Intramural or interstitial portion
• The isthmus
• Ampulla
• Infundibulum
• Fimbriae

Fallopian Tube

Layers

• There are three layers—serous, muscular (inner circular and outer longitudinal) and the peritoneal layer.
• The mucosal layer has columnar ciliated epithelium cells that facilitate the ovum to move towards the uterus.

Functions

• Transport of gametes.

• Provides the site of fertilization and survival of the zygote through its secretion.

• Blood supply: By the uterine and ovarian arteries and veins.
• Lymphatic drainage: Drainage is via ovarian vessels to the para-aortic nodes and uterine vessels to the internal iliac chain.
• Nerve supply: By the uterine and ovarian nerves.

Ovaries

The ovaries are the paired female gonads that form the female gamete. They are of almond shape, pinkish gray in color with the dimensions of 3 cm* 2 cm* 1 cm. They are homologous to testes.

Attachments of the ovary

Structure

The ovary is covered by a single layer of cubical cell known as germinal epithelium. The ovarian structure is divided into :

1. Outer cortical(Cortex)
2. Inner medulla region.

• Blood Supply

Arterial supply is by the ovarian artery. Venous drainage is into the inferior vena cava on the right side and the left renal vein on the left side.

• Lymphatics

Lymphatic drainage to the para-aortic lymph nodes.

• Nerve Supply

From the ovarian plexus.

Muscles of the pelvic floor

MUSCLES AND FASCIA IN RELATION TO THE PELVIC ORGANS

Superficial muscle layer of the pelvic floor

Deep muscle layer of the pelvic floor

Perineum

The perineum is a part of the pelvis that contains the external genitalia and anus.

Anatomical Perineum

It is the part present between the genitals (vaginal opening) and the anus. It is bounded:

• Above by the inferior surface of the pelvic floor.

• Below by the skin present between the buttocks and the thighs.

• Laterally by the ischiopubic rami, ischial tuberosities and sacrotuberous ligaments posteriorly by the coccyx.

• The diamond-shaped bony pelvic outlet is divided into two triangles:
• The urogenital triangle
• The anal triangle.

Muscles of perineum

Obstetrical Perineum

It is also known as the perineal body or the central point of the perineum. The pyramidal shape tissue is located between the vagina and the anal canal. It measures about 4 cm. The base is covered by the perineal skin and the apex, which is the deepest part is formed from pubococcygeus muscle fibres.

Fascia

• Two layers of superficial perineal fascia called colles fascia.

• Inferior and superior layer of urogenital diaphragm.

Pelvic Fascia

Fascia is a thin casing of connective tissue that surrounds and holds the pelvic organs, muscles, and nerve fibers in place.

• Fascia on the pelvic wall: It is rough and membranous. It typically covers the obturator internus and pyriformis and is attached to the bone.

The pelvic nerve lies outside the fascia and the blood vessels lie inside the area of the fascia.

• Fascia on the pelvic floor: It is loose in elasticity.

The parietal layer covers the superior and inferior surface of the pelvic floor floor. It also covers the anal canal.

Pelvic Cellular Tissue

The pelvic tissue lies between the peritoneum and the pelvic floor. It fills all the empty space present in between them. It consists of fatty tissue, connective tissue and unstriated muscle fibres.

Importance

• It supports the pelvic organs.

• It protects the blood vessels of the uterus by covering them with a thin sheath.

• Marked hypertrophy occurs during pregnancy to widen up the spaces.

Pelvis Ureter

The ureters are the hollow muscular tubes extended from the kidney to the bladder. It is about 13 cm long with a diameter of 5 mm. The ureter is a retroperitoneal organ.

Urinary Bladder

The urinary bladder is a hollow distensible organ with a capacity of about 450 ml. It can retain the urine up to 3-4 litres. The empty bladder is pyramidal, and the distended urinary bladder is ovoid in shape.

Female Urethra

The final passage of the urine goes out of the body through the duct or a canal known as the urethra. It extends from the neck of the bladder to the external urethral meatus. It opens about 2.5 cm below the clitoris. It is 4 cm long with a diameter of 6 mm which is comparatively shorter than the male’s urethra. Thus females are more prone to get urinary tract infections. Numerous tubular glands called paraurethral glands open into the lumen of the urethra through ducts.

Breast

The breast is the large compound secretory gland. It is a modified sebaceous glands. It is bilaterally present accessory gland in the female reproductive system responsible for the production and storage of the breast milk, the only preferred source of nutrition for the babies till 6 months of age.

The female breast

Structure

• The breast weighs about 200-300 grams.
• The mature breast contains 20% glandular tissue and 80% fat and
• the rest are the connective tissue.
• Each breast contains12-20 lobes. Each lobe has 10-100 lobules. Each lobule has an alveoli, the structures containing acini cells which produce the milk and store it. Each lobe has a lactiferous duct. Many lactiferous ducts carry the milk from the lobe to the surface of the nipple.
• The alveoli is surrounded by myoepithelial cells, which help in the contraction of the alveoli and the release of breast milk in the lactiferous duct under the influence of oxytocin.

Lobe unit

• The outer central part of the breast which is highly pigmented is known as the areola with a diameter of 2.5 cm.
• Montgomery’s glands are the glands present in the periphery of the areola which produces sebum-like substances to lubricate the areola or the nipple during pregnancy or breastfeeding.
• The nipple is the muscular projection that is covered by pigmented skin. It is highly vascularised.
• The milk is stored in the ampulla beneaththe nipple.

Support

Cooper’s ligaments or the suspensory ligaments, are the fibrous septa supporting the breast by attaching it with the pectoral fascia.