The Reproductive system

By sumanOn September 23, 2023September 23, 2023

Female Reproductive System

Introduction: The female reproductive system is made up of both primary and secondary sex organs. Females’ major sex organs are a pair of ovaries, which produce ova or eggs and secrete female sex hormones such as progesterone and oestrogen. The uterus, fallopian tubes, cervix, and vagina are the other accessory sex organs. The labia minora, labia majora, and clitoris are the external genitalia. The mammary glands are not genital organs, yet they play an essential part in the female reproductive system.

Female Reproductive system producing female gametes (Ovum) and reproductive hormones, the female reproductive system also has to support the developing foetus and deliver it to the outside world, much like the male reproductive system. The female reproductive system is mostly inside the pelvic cavity, unlike the reproductive system of men. Remember that the female gonads are the ovaries. They create a gamete that is known as an oocyte.

Female Reproductive system is divided in to two main part-

External Genital/Reproductive Organ
Internal Genital/Reproductive Organ

EXTERNAL GENITAL ORGANS/EXTERNAL REPRODUCTIVE ORGAN

External female genital organs may call as pudendum/Vulva.

These are the External genital organs-

Mons pubis
Labia majora
Labia minora
Clitoris
Vestibules of the vagina
Bulbs of the vestibules
Greater vestibular glands
Mons pubis: The rounded, padded prominence located in front of the symphysis pubis is known as the mons pubis. Subcutaneous fat accumulates to make it. It is covered in pubic hair, with a roughly horizontal top limit to the hair bearing area.
Labia majora (Greater lip):
Labia majora is the two thick skin folds that enclose by fat and it is define the lateral limits of the pudendal deft.
Outside surfaces of labia majora is hairy, while their inner surfaces are covered in enormous sebaceous glands.
The anterior commissure is formed by connecting the bigger anterior ends below the mons pubis.
The posterior commissure is the skin that connects the less noticeable posterior ends of the labia.
The gynaecological perineum is the 2.5 cm long area between the posterior commissure and the anus.
Labia minora (Lesser lip):
Labia minora are two tiny folds of skin located within the pudendal cleft.
Each labium minus separates into two layers anteriorly; the upper layer joins the corresponding layer on the other side to produce the clitoris prepuce.
Similarly, the bottom layers of the two sides unite to produce the clitoris frenulum. The fourchette is formed posteriorly by the meeting of the two labia minora.
Numerous sebaceous glands can be seen on the inner surface of the labia minora.
Clitoris:
The clitoris is an erectile organ that is related to the penis. However, it is not crossed by the urethra.
It is located in the anterior section of the pudendal cleft. The clitoris body is composed of two corpora cavernosa surrounded in a fibrous sheath and separated in part by an imperfect pectiniform septum.
There is no corpus spongiosum. The glans surface is extremely sensitive and plays a vital role in sexual responses.
Vestibule: A vestibule is a triangular space formed by the clitoris, the fourchette, and the labia minora on either side. There are four entrances to the vestibule:
Urethral opening: The opening is located about 2.5 cm posterior to the clitoris in the midline, immediately in front of the vaginal entrance. Skene’s glands are located on both sides of the urethral opening.
Vaginal opening or introitus: This varies in size and shape and occupies the posterior two-thirds of the vestibule. The labia minora closes the entrance in virgins and nulliparae, although it may be visible in parous women.

It is fully closed by a mucous membrane septum called the hymen. The form of the membrane varies, although in virgins it is commonly round or crescentic.

The hymen is typically ruptured at the time of marriage. The hymen is severely lacerated after childbirth and is known as the carunculate myrtiformes.

It is bounded on both sides by stratified squamous epithelium.

Bartholin’s gland openings: There are two Bartholin’s glands (greater vestibular glands) on each side. They are located in the posterior section of the labia majora and open on each side of the vaginal opening.

They have a pea form and a yellowish white colour. It secretes a lot of alkaline mucus during sexual excitation, which assists with lubrication. Each gland has a duct about 2 cm long that exits into the vestibule outside the hymen. Columnar epithelium lines the duct.

Perineum: The perineum is a triangle region that extends from the base of the labia minora to the anal canal. It is made up of connective tissue, muscles, and fat. It also provides connection to the pelvic floor muscles.

Blood supply, Lymphatic drain and Nerve supply

Blood Supply: Blood flow is provided through the internal and exterior pudendal arteries. The blood flows through the veins that relate to it.
Lymphatics drain: into the inguinal lymph nodes and the internal iliac lymph nodes.
Nerve supply: Nerve supply is provided by the branches of the pudendal nerve. The genitofemoral nerve (L1 and L2) supplies the front section, and the pudendal branches of the posterior cutaneous nerve of the thigh (S1, S2, and S3) supplies the posterior part. The vulva is nourished by the pudendal nerve’s labial and perineal branches (S2, S3, and S4).

INTERNAL GENITAL/REPRODUCTIVE ORGANS

The internal organs of the female reproductive system lie in the pelvic cavity and consist of the vagina, uterus two uterine (fallopian) tube and two ovaries.

Vagina:
The vulva is a fibromuscular membranous sheath that connects the uterine cavity to the outside world.
It is a tube that allows menstrual flow and uterine secretions to escape. It receives the penis and discharged sperm during sexual intercourse and allows the foetus to exit upon birth.
In erect position, the canal is directed upward and backward, producing a 45° angle with the horizontal.
The vaginal long axis is almost parallel to the plane of the pelvic inlet and at right angles to that of the uterus.
In the adult, the anterior wall is about 7.5 cm and posterior wall is about 9 cm long. The canal has a diameter of around 2.5 cm and is broader in the upper half and narrowest at the introitus.
It has sufficient distensibility, as seen during birthing.

Hymen: A thin layer of mucous membrane that stretches across the vaginal canal just inside the external opening. It is generally unfinished to let menstrual flow to pass through and is stretched or entirely pulled away by sexual intercourse, tampon insertion, or childbirth.

The vaginal wall is composed of three layers: an exterior layer of areolar tissue, a middle layer of smooth muscles, and an interior lining of stratified squamous epithelium that creates ridges or rugae. It lacks secretory glands, but cervical secretion keeps the surface moist.

Lactobacillus acidophilus, a bacterium that secretes lactic acid, is generally present between adolescence and menopause, keeping the pH between 4.9 and 3.5.

Most other bacteria that may contaminate the vagina from the perineum or during sexual contact are inhibited by the acidity.

Blood supply, Lymph drainage and nerve supply in the vagina:

Arterial supply: The uterine and vaginal arteries, which are branches of the internal iliac arteries, form an arterial plexus around the vagina.
Venous drainage: The internal iliac veins are drained by a venous plexus located in the muscle wall.
Lymphatic drainage: This is accomplished via the deep and superficial iliac glands.
The supply of nerves: This comprises of parasympathetic fibre from the sacral outflow, sympathetic fibres from the lumbar outflow, and pudendal nerve somatic sensory fires.

Function of vagina:

The vagina acts as the receptacle for the penis during sexual intercourse (coitus), and provides an elastic passageway through which the baby passes during childbirth.

Uterus:
The uterus is a hollow, muscular, pear-shaped organ that is flattened anteroposteriorly. It is located in the pelvic cavity between the urine bladder and the rectum.
In most women, it leans forwards (anteversion) and bends forwards (anteflexion) virtually at right angles to the vagina, generating the vesicouterine pouch between the two organs.
When the body is upright, the uterus is practically horizontal. It is roughly 7.5 cm long, 5 cm wide, and 2.5 cm thick. It weights between 30 and 40 g.

The three main parts of the uterus are the fundus, body and Cervix.

Fundus: This is the dome-shaped region of the uterus just above the uterine tube openings.

Body: This occupies up the top two-thirds of the uterus. It has a pear form and is narrowest inferiorly at the internal OS, where it joins the cervix.

Cervix (‘neck’ of the uterus): The cervix is the lower end of the uterus (womb). It is located at the top of the vagina. It measures approximately 2.5 to 3.5 centimetres (1 to 1.3 inches) in length. The cervix is traversed by the cervical canal. It allows menstrual blood and a foetus (baby) to travel from the mother’s uterus into the vagina. To fertilise the egg, sperm travel from the vagina up the cervical canal into the uterine cavity, then into the fallopian tubes.

Structure of the Uterus: The walls of the uterus are composed of three layers of tissue: perimetrium, myometrium and endometrium.

Perimetrium: The cervix (uterine ‘neck’) is the thinnest part and is usually around 2.5 cm length. It protrudes through the vaginal anterior wall, opening into it at the external os.

Structure:

The uterine walls are made up of three layers of tissue: perimetrium, myometrium, and endometrium.
Perimetrium is peritoneum that is distributed differentially on the various uterine surfaces. It can be envisioned as a blanket spread from above over the uterus, uterine tubes, and ovaries, covering mostly the anterior, top, and posterior regions of the uterus.
It lies over the fundus and the body anteriorly, where it is folded onto the upper surface of the urine bladder.
The peritoneum covers the fundus, the body, and the cervix posteriorly before folding back on to the rectum to form the rectouterine pouch (of Douglas).
Because the peritoneum forms a double fold with the uterine tubes in the top free border, only the fundus is covered laterally. This double fold is the wide ligament, which connects the uterus to the sides of the pelvis at its lateral extremities.
Myometrium: This is the uterine wall’s thickest layer of tissue. It’s a tangle of smooth muscle fibres, areolar tissue, blood arteries, and nerves.
Endometrium
Columnar epithelium covers a layer of connective tissue that contains numerous mucus-secreting tubular glands.
It receives a lot of blood from spiral arteries, which are uterine artery branches.
The upper layer is the functional layer, which thickens and becomes rich in blood vessels throughout the first part of the menstrual cycle.
This layer is shed during menstruation if the ovum is not fertilised and does not implant.
The basal layer, which is located near to the myometrium, is not lost during menstruation. During each cycle, the fresh functional layer is recreated from the permanent layer.
This mucous membrane lines the upper two-thirds of the cervical canal. Lower down, however, the mucosa transforms into stratified squamous epithelium, which joins with the vaginal lining.

Blood supply, lymph drainage and nerve supply of the uterus:

Blood supply: This is accomplished through the uterine arteries, which are branches of the internal iliac arteries. They extend up the uterine lateral sides between the two lavers of the broad ligaments. They supply the uterus and uterine tubes, as well as the ovaries.
Venous drainage: The veins travel along the same path as the arteries, eventually draining into the internal iliac vein.
Lymph drainage: Lymph drainage occurs when lymph flows from the uterus and uterine tubes to the aorta lymph nodes and node groups related to the iliac blood vessels via deep and superficial lymph veins.
Nerve supply: The nerves that nourish the uterus and uterine tubes are made up of parasympathetic fibres from the sacral outflow and sympathetic fibres from the lumbar outflow.

Supporting structures of the uterus:

The uterus is supported in the pelvic cavity by surrounding Organs, muscles of the pelvic floor and ligaments that suspend it from the walls of the pelvis.

Broad ligaments

These are generated by a peritoneum fold on each side of the uterus. They hang down from the uterine tubes as though draped over them, and their lateral ends are linked to the pelvic sides.

The uterine tubes have been enclosed in the top free border, and near the lateral ends, they penetrate the posterior wall of the broad ligament and emerge into the peritoneal cavity, while the ovaries are attached to the posterior wall, one on each side. Between the lavers of the wide ligaments, blood and lymph vessels, as well as nerves, flow to the uterus and uterine tubes.

Round ligaments: These are bands of muscle and fibrous tissue that run between the uterus’s two layers of wide ligament, one on each side. They go along the sides of the pelvis, into the inguinal canal, and finally fuse with the labia majora.
Uterosacral ligaments: These originate in the cervix and vaginal posterior walls and extend backwards, one on each side of the rectum to the sacrum.
Transverse cervical (cardinal) ligaments: These extend one from each side of the cervix and vagina to the pelvic side walls.
Pubocervical ligament: This connects the transverse cervical ligaments on each side of the bladder to the posterior surface of the pubic bones.

Functions of the uterus:

After puberty, the endometrium undergoes a monthly cycle of changes known as the menstrual cycle, which is regulated by hypothalamic and anterior pituitary hormones.
The menstrual cycle prepares the uterus to receive, nurturing, and protect an ovum that has been fertilised. Typically, the cycle lasts between 26 and 30 days.
If the ovum does not fertilise, the functional layer (endometrium layer) of the uterine lining sheds and a new cycle begins with a brief period of vaginal bleeding (menstruation).
The zygote embeds itself in the uterine wall if the ovum is fertilised. The uterine muscle expands to accommodate the developing baby, known as an embryo for the first 8 weeks and a foetus for the rest of the pregnancy.
Uterine fluids nourish the embryo before it implants endometrium, and endometrial cells nourish the quickly developing ball of cells after implantation.
This is only enough for the first few weeks until the placenta takes control.
The placenta, which is connected to the foetus via the umbilical cord, is also securely attached to the uterine wall and is the structure that gives the growing infant with oxygen and nourishment while also allowing it to expel waste.
During pregnancy, the placenta also serves an important endocrine function.
It secretes a lot of progesterone, which keeps the muscular uterine walls from contracting in response to the fetus’s progressive uterine stretching.
The hormone oestrogen, which enhances uterine contractility, becomes the major sex hormone in the blood at term (the end of pregnancy).
Furthermore, oxytocin is secreted from the posterior pituitary gland and induces uterine muscle contraction.
Positive feedback regulates oxytocin release. The uterus expels the baby with intense rhythmical contractions during labour.
Uterine tubes/Fallopian Tube: The uterine (Fallopian) tubes are approximately 10 cm long and extend from the uterus’s sidewalls between the body and the fundus.

They are located near the ovaries in the top free border of the wide ligament, and their trumpet-shaped lateral ends puncture the posterior wall, opening into the peritoneal cavity. Fimbriae are finger-like extensions on the ends of each tube.

The ovarian fimbria, which is closely associated with the ovary, is the longest of them.

The uterine tubes are bilateral uterine appendages situated at the superior region of the uterus cavity.

These tubes escape the uterus through a region known as the cornua, connecting the endometrial and peritoneal cavities.

The fallopian tube is divided into four sections (lateral to medial)-

Fimbriae are finger-like, ciliated projections that catch the ovum from the ovary’s surface attached to an infundibulum, which is a funnel-shaped aperture near the ovary.

The ampulla is the uterine tubes’ widest part. Fertilisation is frequently done here.

The isthmus is a thin portion of the uterine tubes that connects the ampulla to the uterine cavity.

Structure

The uterine tubes are covered with peritoneum (a broad ligament), have a smooth muscular middle layer, and are coated with ciliated epithelium. Blood and nerve supply, as well as lymphatic outflow, are the same as in the uterus.

Functions of the Fallopian tube: Peristalsis and ciliary movement drive the ovum from the ovary to the uterus via the uterine tubes. The uterine tube secretions nourish both the ovum and the spermatozoa.

The ovum is normally fertilised in the uterine tube, and the zygote gets pushed into the uterus for implantation.

4. Ovaries

The ovaries are the female gonads (glands that produce sex hormones and the eggs), and they are located in a shallow depression on the pelvic lateral borders. They measure 2.5-3.5 cm in length, 2 cm in width, and 1 cm in thickness.

The ovarian ligament connects each to the top section of the uterus, while the mesovarium connects each to the rear of the wide ligament. The mesovarium is where blood arteries and nerves connect to the ovary.

Structure

The ovaries have two layers of tissue.

Medulla

This lies in the centre and consists of fibrous tissue, blood vessels and nerves.

Cortex

This is what surrounds the medulla. It has a connective tissue structure, or stroma, that is covered by germinal epithelium.

It comprises ovarian follicles at varying stages of maturity, each containing an ovum. The ovaries are inactive until puberty, but the stroma already includes immature (primordial) follicles, which the female has from birth.

During the reproductive years, one or more ovarian follicles (Graafian follicles) mature, rupture, and discharge their ovum into the peritoneal cavity every 28 days. This is known as ovulation, and it occurs during the majority of menstrual cycles.

Following ovulation, the burst follicle develops into the corpus luteum (meaning “yellow body”), which leaves a little permanent scar of fibrous tissue on the surface of the ovary called the corpus albicans (meaning “white body”).

Blood supply, lymph drainage and nerve supply

Arterial supply is provided by the ovarian arteries, which branch from the abdominal aorta slightly below the renal arteries.

Venous drainage: This is into a plexus of veins behind the uterus from which the ovarian veins emerge. The right ovarian vein drains into the inferior vena cava, while the left drains into the left renal vein.

Lymph drainage: This is to the lateral aortic and preaortic lymph nodes. The lymph vessels follow the same path as the arteries.

Nerve Supply: The ovaries are nourished by parasympathetic nerves from the sacral outflow and sympathetic neurons from the lumbar outflow.

Functions of Ovary

A female child’s ovaries contain over a million immature follicles at birth, albeit many of them die before puberty begins.
The hypothalamus and the anterior pituitary gland regulate their maturation by secreting gonadotrophins (follicle stimulating hormone, FSH, and luteinizing hormone, LH), both of which act on the ovary.
Furthermore, the ovary has endocrine activities and releases hormones that are necessary for the physiological changes that occur during the reproductive cycle.
The follicle is the source of these hormones, which include oestrogen, progesterone, and inhibin. The follicle secretes increasing levels of oestrogen during the first half of the cycle, as the ovum develops within it.
However, during ovulation, the corpus luteum secretes predominantly progesterone, with little amounts of oestrogen and inhibin. The significance of this is covered in the section on the menstrual cycle.

Puberty in the female:

Puberty is the maturation of the internal reproductive organs, which occurs between the ages of 12 and 14.

This is known as the menarche, and it marks the start of the reproductive era. Puberty is defined by an increase in the production of reproductive hormones and the beginning of the female reproductive cycle.

The anterior pituitary gonadotrophins, FSH and LH, regulate ovarian function.

The ovaries begin to generate Oestrogens under the influence of gonadotrophins, which are the primary stimuli for the development of the physical changes associated with puberty.

These modifications, known as secondary sexual characteristics, include:

Maturation of the uterus, uterine tubes, and ovaries.
Breast development and enlargement.
Increased pubic and axillary hair growth.
Heightening and broadening of the pelvis.
Increased fat deposition in the subcutaneous tissue, particularly at the hips and breasts.

Breasts

The breasts, also known as mammary glands, are female reproductive system accessory glands. They exist in males as well, although only in a basic form.

Structure

The mammary glands, often known as the breasts, contain different amounts of glandular tissue, which is supported by fatty tissue and fibrous connective tissue that anchors the breast to the chest wall.
Each breast has roughly 20 lobes, each with a number of glandular structures called lobules that generate milk. Lobules open into tiny lactiferous ducts that drain milk into the nipple.
Subcutaneous fat covers the breast, which is supported by fatty and connective tissues that run through it and surround the lobules.
To stimulate milk production, glandular tissue proliferates (hyperplasia) in the breastfeeding breast and then recedes after lactation ends.

Nipple

The areola is a tiny conical prominence in the centre of the breast that is surrounded by a pigmented region. Numerous sebaceous glands (Montgomery’s tubercles) on the surface of the areola lubricate the nipple during breastfeeding.

Blood supply, lymph drainage and nerve supply of the breast:

Arterial provision

The axillary arteries’ thoracic branches, as well as the internal mammary and intercostal arteries, supply blood to the breasts.

Drainage via the veins: An anastomotic circle forms at the base of the nipple, from which branches convey venous blood to the circumference and terminate in the axillary and mammary veins.

Lymphatic drainage: This is primarily into the axillary lymph vessels and nodes. If the superficial pathway is blocked, lymph may flow into the internal mammary nodes.

Nerve supply

The branches of the 4th, 5th, and 6th thoracic nerves, which contain sympathetic fibres, supply the breasts.

In the breast, there are numerous somatic sensory nerve endings, particularly near the nipple. Sucking stimulates these touch receptors, sending impulses to the brain and increasing oxytocin secretion, boosting milk release.

Functions of breast: Until adolescence, female breasts are tiny and undeveloped. Following that, they develop and grow under the influence of oestrogen and progesterone.

These hormones induce additional growth during pregnancy.

After the infant is born, the anterior pituitary hormone prolactin encourages milk production; the posterior pituitary hormone oxytocin stimulates milk release in response to the nipple stimulation by the sucking baby, via a positive feedback process.