2.2 FEMALE REPRODUCTIVE SYSTEM
The female reproductive organs or genitalia are divided into external and internal organs
External Genitalia:
This is collectively known as the vulva or pudendum. It consists of the following;
Mons pubis
Labia majora
Labia minora
Vestibule of the vagina
Clitoris
Greater vestibular glands or Bartholin's glands,
Fourchette,
Perineum.
Mon pubis or Mons veneris: It is also known as mount of Venus. It is a pad of fibro- fatty tissue lying on the pubic bone which is covered by hair at puberty. It serves as a coital buffer and protects the external organs. It divides to become continuous with labium majus of each side.
Labia Majora or Greater Lips: These are 2 folds of fats and areola (connective) tissue, covered by skin and pubic hair on the outer surface. They contain a large number of sebaceous glands. They form the boundary of the vulva as they arise from the mons pubis and merges into the perineum behind.
Labia Minora or Lesser Lips: These are 2 folds of (Smaller) skin in between the labia majora. Anteriorly they divided to enclose the clitoris, while posteriorly they fuse to form the fourchette. The minora lips are more vascular and more sensitive. They also contain numerous sebaceous glands. They cover the vaginal and urethra orifice.
Clitoris: This is a small rudimentary organ which lies between the labia majora and minora. It is the most sensitive part of the female hence corresponds to the penis in male. It consist of erectile tissue and sensory nerve endings which makes it the centre of sexual sensation for the female.It has no reproductive significance.
Vestibule: It is the cleft between the labia minora which houses the opening of the vaginal and urethral orifice. Is the triangular area bounded anteriolaterally by the labia minora and posteriorly by the fourchette. It contains the urethral meatus located approximately 2 to 3 cm posterior to the clitoris, immediately in front of the vaginal opening.
Vestibular or Bartholin’s gland: They are 2 pea-sized organs situated, 1 on each side of the vaginal opening. They have ducts which open into the vestibule to lubricate the vulva by means of secreting a glairy fluid which serves as lubricant. Are two small rounded structures situated just posterior to the vestibular bulbs.
Vaginal Orifice: It is the opening leading to the vaginal tube and the internal genitalia.
Hymen: It is a thin mucous membrane which partially covers the vaginal orifice. It may stretch or tear during first sexual intercourse.
Urethral Orifice: It is the opening through which the urine passes from the bladder.
Perineum: It isthe area which extends from the base of the labia minora to the anal canal. It is roughly triangular and consists of connective tissue, muscle and fats. It gives attachment to the muscle of the pelvic floor.
Internal Genitalia:
The internal organs of the female reproductive system lie within the pelvic cavity and consist of the following;
1. Vagina: It is the passage which connects the external and internal organs of reproduction. It starts from the vestibule to the cervix, passing upwards and backwards into the pelvis at an angle of 450
Structure: The posterior wall is about 9-10cm long while the anterior wall is about 7.5cm long. This is due to the angle of insertion of the cervix through the anterior wall which is called the vault (it is the upper end of the vagina where the cervix projects into). The vaults forms a circular recess called the fornices.
The vagina has 3 layers as follows: -outer layer of areola tissue, middle layer of smooth muscles and inner layer of satisfied squamous epithelium that forms the rugae (small folds). The rugae allow the vagina to stretch during intercourse and childbirth. The vagina has no secretory glands but the surface is moisten by the secretions from the cervix. Within the childbearing age, bacteria called lactobacillus acidophilus are normally present and it secretes lactic acid which makes the pH of the vagina to be acidic (between 4.9 and 3.5). The acidic nature of the vagina inhibits the growth of most pathogenic micro-organisms which may otherwise have access through the perineum.
Position- Anteriolylies the bladder and the urethra
- Posteriorly lies the pouch of Douglas, the rectum and the perineal body.
- Laterally the pelvic fascia and the ureters pass beside the cervix, at thelower angle are the muscles of the pelvic floor.
Functions
1. Allows the escape of menstrual floor
2. It receives the penis and ejected sperm during intercourse
3. It provides an elastic passage way for the fetus during delivery.
2. Cervix: It is the opening which links the vagina to the uterus. It measure about 2-5cm in length.
3. Uterus: It is a hollow, muscular, pear shaped organ which lies in the pelvic cavity between the urinary bladder and the rectum. It leans forward which is known as anterversion, and bends forward on itself which is known as anteflexion. When standing the result is almost horizontal position with the fundus resting on the bladder.
Structure: – the non-gravid uterus is about 7.5cm long, 5cm wide and 2.5cm, in depth (each wall is 1.25cm thick). The cervix forms the lower one third of the uterus. It consists of the fundus, body, cornua, cavity, isthmus, and cervix. Internal and external 0S.
Parts of the uterus:
Fundus – It is the domed upper wall between the insertions of the uterine tubes.
Body or corpus – This makes up the upper 2/3 of the uterus and it is the greater part.
Cornua – These are the upper outer angles of the uterus where the uterine tubes join.
Cavity – It is a potential space between the anterior and posterior walls. It is triangular in shape with the base of the triangle at the upper portion.
Isthmus – It is a narrow area between the cavity and the cervix, which is 7mm long. It enlarges during pregnancy to form the lower uterine segment.
External 0S- It is a small round opening at the lower end of the cervix. After childbirth it becomes a transverse slit.
Cervix or neck – It is the lowest part of the uterus which protrudes into the vagina. The upper half, being above the vagina is known as the supravaginal portion while the lower half is the infravaginal portion.
Internal 0S (Mouth) – Is the narrow opening between the Isthmus and the cervix.
The cervical canal lies between the two openings and it is the continuation of the uterine cavity
Layers of the Uterus
The uterus has three layers namely; the Endometrium, the Myometrium and the Perimetrium.
Endometrium: It is the inner lining of the uterine cavity which consists of ciliated columnar epithelium containing a large no of mucus-secreting tubular glands (mucus membrane). This is called the functional layer and it lies on top of a second layer called the basal layer made of connective tissue. The functional layer constantly changes in thickness throughout the menstrual cycle and it is sheds when ovulation do not takes place. The basal layer does not change but provides the foundation from which the functional layer regenerates
Myometrium: It is a muscle coat and the thickest layer of tissue in the uterine wall. It is thickest in the upper part of the uterus and is sparser in the isthmus and cervix. Its fibres run in all directions and interlace to surround the blood vessels and lymphatic’s which passes to and from the endometrium. The outer layer is formed of longitudinal fibres which are continuous with those of the uterine tube, the uterine ligaments and the vagina.
Perimetrium: It is a double serous membrane which is an extension of the peritoneum that is draped over the uterus covering all but a narrow strip on either side of the anterior wall of the supra-vaginal cervix from where it is reflected up over the bladder.
Position
Posteriorly - lies the recto uterine pouch of Douglas and rectum.
Anteriorly - lies the utero vesicle pouch and the bladder.
Laterally - on either side are the broad ligament, the uterine tubes and the ovaries’.
Superiorly - lies the intestine.
Inferiorly - lies the vagina.
Functions
The uterus exists to nourish and shelter the fetus during pregnancy.
In preparation for the pregnancy it undergoes the menstrual cycle.
4. Uterine Tubes: These are 2 narrow tubes, each measuring about 10cm. long. They are lined by mucus membrane of ciliated cubical epithelium which is in folds called plicae. These folds slow the ovum down on its way to the uterus. In this lining there are goblets cells which produce a secretion containing glycogen to nourish the ovum.
The uterine tube is described in four portions as follows:
The interstitial portion – lying within the wall of the uterus. It measures about 1.25cm long and 1mm wide within the lumen.
The Isthmus – It is a narrow path which extends from the uterus for about 2.5cm.
The ampulla – Is the wider portion where fertilization usually occurs. It is about 5cm long.
The infundibilum – Is the funnel-shaped fringed end which is composed of many processes known as fimbrae.
Functions
Collect and propel the ovum toward the uterus by peristalsis and ciliary movement.
Receives the spermatozoa (the mucus secreted by the mucosa aid the spermatozoa to move)
Provides a site for fertilization
Nourishes the fertilized ovum throughout it journey to the uterus.
Position: The uterine tubes extend laterally from the cornua of the uterus towards the side walls of the pelvis. They arch over the ovaries, the fringe ends hovering near the ovaries in order to receive the ovum, anteriorly, posteriorly and superiorly – the perinealcavity and the intestines.
Lateral – Side walls of the pelvis
Inferior – The broad ligaments and ovaries lie below the tube.
5. The Ovaries: The ovaries are 2 oval-shaped firm structures with an average 3-5cm in its widest diameter. They are the female gonad which produces the ova and the sex hormones (oestrogen and progesterone).
Structure
The ovaries consist of 2 layers:-
The medulla is the inner part and consists of fibrous tissues, blood vessels and nerves.
The cortex surrounds the medulla. It contains ovarian follicles in various stages of maturity, each contains an ovum. The cortex is the functioning part of the ovary. Before puberty the ovaries are inactive but unready contains primordial follicles since from birth. At puberty in about every 28days, one Graafian follicle matures and ruptures to release the ovum into the peritoneal cavity.
Functions
Produces ova
Production of sex hormones (oestrogen and progesterone)
