FEMALE REPRODUCTIVE SYSTEM

Vulva is divided into the mons pubis, labia minora, labia majora, Bartholin’s gland, clitoris, and the perineum as well as the opening of the urethra. These components collectively refer to the vulva which is the only outer part of the female reproductive system, as all other structures are internal (Fig. 1).

In females, there are two ovaries: the right ovary and the left ovary functioning as glands to produce the eggs in addition to the female hormones estrogen and progesterone. They appear in the pelvic cavity just below the fallopian tubes, attached by ligaments to the uterus. More than 1,000,000 follicles exist in each female infant, and around 40,000 of the follicles remain by the time of menarche, with the rest having been absorbed by the body (Fig. 2). 

After the ovary has produced the ovum, the fimbriae pick it up. Then it moves towards the fallopian tube, which is a funnel-shaped duct. The wall of the fallopian tube is lines with muscles and microscopic hairs called the cilia. When these muscles contract, wave-like movements result, which with the rhythmic beating of the cilia push the ovum. The cilia also facilitate the movements of sperm towards the egg so that conception occurs, most commonly in the part of the fallopian tube closest to the ovary (Fig. 3).    

The uterus is divided into the body, the fundus and the cervix (Fig. 4). While the body is located low in the pelvic cavity, the uterine fundus lies above the entrance of the fallopian tubes with the cervix extending from the uterus into the vagina. As a hollow cavity, the uterus is vital for the development of a zygote. The walls of the uterus are composed of three thick layers (Fig. 4): 

• The endometrium or the innermost layer names as, where a zygote implants and grows. 
• The myometrium or the muscular middle layer or which facilitates the movements of the baby in the vagina through its rhythmic contractions during childbirth. 
• The perimetrium or the outer, serous layer, attached to the lining of the abdominal and pelvic organs.

It is a main part of the female genital tract occupying the space from the cervix to the entry of the vulva. As a fibromuscular pathway, the vagina, during sexual intercourse, receives semen ejaculated by a male penis. Also, it is the canal through which the body gets rid of menstrual fluids, and through which the uterus is connected to the outside world (Fig. 5). 

Female breasts are two protuberances sited in the upper ventral part or on the anterior chest wall. They are mammary glands responsible for releasing milk with the aim of feeding babies. They start milk production during the final weeks of pregnancy. Breasts are also composed of lactiferous ducts that move the milk from the lobules to the nipple, the areola referring to the nipple and its surrounding pigmented area where a baby attaches to suckle, fat and connective tissue. With the increasing quantities of oestrogen and progesterone during puberty, breasts grow and mature (Fig. 6).

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The body’s changes associated with the development of an egg and the possibility of pregnancy refers to the menstrual cycle, the length of which differs from woman to woman. However, it generally takes around 28 days, lessening or expanding to 20 or 40 days, respectively in some cases. Also, the length becomes irregular in some women with stress, excessive physical activity or weight changes. The cycle begins with the first day of the menstrual period, the cycle starts, and the day before the next period starts is the end of the cycle. Menstrual phase, follicular phase, ovulation and luteal phase are the four phases involved in each cycle (Fig. 7).

It is a part of the menstrual cycle in which the ovary is instructed by follicle-stimulating hormone (FSH) to develop between 10 and 20 follicles each containing an immature egg. With the growth of the follicles, the levels of oestrogen increase in blood, and hence gonadotrophin-releasing hormone (GnRH) is secreted by the hypothalamus in the brain. GnRH is a chemical functioning to produce luteinizing hormone (LH) and more FSH from the pituitary. Also, with the increasing amount of the oestrogen, of the lining of the uterus or the endometrium acquires around 3 mm spongy thickening. In normal circumstances, only one mature egg is developed out of the follicles while the others break down and the body reabsorbs them (Fig. 7).

The process of releasing one mature egg from one of the ovaries, as a result of increasing levels of LH, FSH and consequently the oestrogen, is defined as the ovulation. The ovum moves down to the fallopian tube and if fertilized by sperm, 5 days are needed for the zygote to reach the uterus. If not fertilized, the ovum can survive between 6-12 hours. Then, it is smashed and get reabsorbed (Fig. 7).

When the corpus luteum, a solid mass, appears on the surface of the ovary as a remnant of the follicle, the luteal or secretory phase starts.  The endometrium is prepared to receive and accept the zygote through releasing hormones, particularly progesterone, by the corpus luteum. Oestrogen is stimulated while FSH and LH are suppressed as a result of the high level of progesterone in blood. The corpus luteum is 6evels occurs with a deterioration in the endometrial lining. Menstruation happens and a new cycle starts. With the presence of fertilization, human chorionic gonadotrophin (hCG) is released by the embryo and so the corpus luteum is maintained (Fig. 7).

It is the last stage of the cycle in which the thickened uterine lining is cleaned with expelling the menstrual fluid, composed of blood, mucus and endometrial cells, out of the body through the vagina. The menstrual period takes from 3–7 days in length. However, it differs among women (Fig. 7).  

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It refers to the process of cell divisions occurring in the ovaries to produce ova eligible to further develop when fertilized. Huge amounts of the female stem cells called oogonia are created during the process of developing female fetus, and primary oocytes or daughter cells are consequently produced. The ovary connective tissue receives these primary oocytes which are enveloped by a single layer of cells to ultimately form the primary follicles. By birth, the oogonia disappear and approximately 1 million of primary oocytes stay in the ovarian follicles throughout childhood, estimated 10 to 14 years. Through oogenesis during puberty, the primary follicles develop to functional eggs. At puberty, about 300,000 oocytes remain, and with the release of FSH (follicle-stimulating hormone) by the anterior pituitary gland, ovulation starts, and few primary follicles are activated monthly. It refers to the ovarian cycle (Fig. 8). 

With the maturation of the follicles, fluid is accumulated in the antrum, in the central chamber. Chromosomes of the primary oocyte are replicated or reproduced as meiosis starts. Two cells with asymmetrical sizes are produced as per the first meiotic division: a secondary oocyte (the bigger cell) and a polar body (the very tiny cell). The secondary oocyte of the follicle emerges from the external surface of the ovary. It takes about 14 days for the follicle to develop. With the secretion of LH by the anterior pituitary gland, ovulation occurs, producing the secondary oocyte with a new name which is the corona radiate (Fig. 9). 

In one of the fallopian tubes, if a sperm manages to unite with the ovulated secondary oocyte, the second meiotic division will be carried out and completed by the oocyte, and consequently the ovum and another polar body are released. The zygote is formed as a result of the combination of the 23 chromosomes of the ovum with those of the sperm. Only one functional egg and three tiny polar bodies result from meiosis, in contrary to that in males which gives four functional sperm. The polar bodies rapidly die for being devoid of cytoplasm. Their only function is to decrease the number of chromosomes in the developing oocyte. If not fertilized by a sperm, meiosis will stop, and the secondary oocyte will collapse. At puberty and with the ability of the ovaries to release oocytes, ovarian hormones are also produced: estrogen and progesterone (Fig. 9). 

Estrogen functions to show up the secondary sex characteristics in the young woman, such as the development of breasts, the growing of the accessory organs of the female genital tract (uterine tubes, uterus, vagina, external genitals), and the increased deposits of fat beneath the skin in general, and particularly in the hips and breasts and menstrual cycle. Estrogen also has metabolic effects. Keeping low blood cholesterol levels and facilitating calcium ion uptake are among the main functions of the estrogen (Fig. 10). 

Progesterone is secreted with the rupture of the follicle and its conversion into the corpus luteum. It works to keep the pregnancy and stimulate the milk production by the breasts. During pregnancy, the placenta, not the ovaries, is the source of the progesterone (Fig. 10). 

As a result of the non-fertilization of a functional egg by a sperm, the menstrual cycle occurs. Three phases are included in the uterine cycle (Fig. 11): 

Menstrual Phase

As an ovum collapses, the superficial functional layer of the thick endometrial lining of the uterus is detaching from the uterine wall. Consequently, the menstrual flow, composed of the detached tissues and blood, is formed and it passes through the vagina for 3 to 5 days. At this phase, women lose around 50 to 150 ml of blood. This phase takes around five days of the menstrual cycle. With the completion of this phase by day 5, new ovarian follicles start to release more estrogens (Fig. 11). 

Proliferative Phase

With the increasing level of estrogens secreted by the growing follicles of the ovaries. The functional layer with glands inside is regenerated by the basal layer of the endometrium. This rejuvenation is associated with an increase in the endometrial blood supply as the endometrium regains its thickness and vascularization. This stage takes from days 6-14. With the end of the proliferative phase, the level of LH increases suddenly in blood and hence ovulation happens in the ovary (Fig. 11).

Secretory Phase

When progesterone is released in high quantities by the corpus luteum, the blood supply of the endometrium is enhanced. Also, the endometrial glands grow again providing the uterine cavity with nutrients which keep a developing embryo till it has implanted if there is fertilization. With the presence of fertilization, a hormone very similar to LH is released by the embryo, allowing the hormones of the corpus luteum to be released constantly. This stage continues from days 15-28 (Fig. 11). 

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It is a sac filled with fluid and develop in the ovary or on its surface during childbearing years, with approximately 2-2.5 cm in size. Although most ovarian cysts are benign, some problems result from larger cysts such as pain and bleeding. Surgical intervention may be required to remove them. To detect the presence of ovarian cysts, pelvic examination, ultrasonography and laparoscopy are required, and sometimes they are found incidentally during another procedure (Fig. 12).

When some benign growths appear in the smooth muscle of the uterus, uterine leiomyoma occurs. Pathogens of UL are unknown. However, a rise in the levels of oestrogen and growth hormone is thought to stand behind this disease. Leiomyomata are harmless in themselves. However, anaemia, infertility and intestinal obstruction can develop as complications. Also, they can threaten pregnancy, causing spontaneous abortion, premature labor or dystocia. This condition can be diagnosed through blood tests, ultrasound examination, laparoscopy or submucosal hysterosalpingography (Fig. 13).

Carcinoma of the breast or breast cancer is a malignant tumor that is fatal to women. It appears in different types. However, invasive ductal carcinoma is the most common type. Other types include medullary carcinoma, inflammatory carcinoma and lobular carcinoma. The danger of the breast cancer lies in it metastasize. It starts in the breast tissue and spread to other sites in the body including the axillary lymph nodes, then the chest wall and skin. Also, it can move to brain and bone. Breast self-examination or mammogram can give the first diagnosis which can be confirmed by biopsy, needle aspiration and needle core, or through taking surgical specimen (Fig. 14).

When abnormal cells grow in the lining of the cervix, carcinoma of the cervix or cervical carcinoma happens. It begins as dysplasia of cervical cells, then develops to become an invasive carcinoma. However, it is curable if it is detected early. It can be easily diagnosed using a Pap smear, and in its early stages, no symptoms appear. It is often associated with the presence of human papillomavirus (Fig. 15). 

It refers to the growth of malignant cells in the ovarian tissues. It is called the “silent killer” for being asymptomatic in the early stages and for it metastasize to the lungs, liver and pelvis before the appearance of any symptom. Even the symptoms experienced in the case of the ovarian carcinoma are non-specific, including distension, lethargy and fatigue. Ultrasound can detect the disease (Fig. 16). 

It is a bacterial infection of the female reproductive organs may involve the fallopian tubes, ovaries and uterus. It is a complication caused by, for example, gonorrhea. As a sexually transmitted infection, PID starts in the vagina and transfers to the uterus, then to the adjacent organs. Several complications are experienced, including peritonitis, infertility and an increased risk of an ectopic pregnancy (Fig. 17). 

When the wall between the urinary bladder and the vagina weakens and ruptures, cystocele occurs. It can develop to the drop of the bladder into the vagina. This condition results from trauma or an increasing pressure on the pelvic muscles and ligaments. Pelvic pressure and urinary frequency are symptoms (Fig. 18). 

It takes place with the falling of the supportive wall of tissues between a female’s rectum and vagina after pregnancy and childbirth. This disease occurs associated with dyspareunia and difficult defecation (Fig. 19). 

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  a. Luteal phase

  b. Ovulation phase 

  c. Menstrual phase 

  d. Follicular phase

  a. Cervix

  b. Ovary 

  c. Uterus

  d. Vagina

  a. Carcinoma of the breast

  b. Carcinoma of the cervix

  c. Carcinoma of the uterus

  d. Carcinoma of the ovary

  a. Progesterone   

  b. GnRH  

  c. FSH

  d. Oestrogen 

  a. Merancke  

  b. Menarche 

  c. Mollarche 

  d. Menstarche 

  a. Luteal phase

  b. Ovulation phase 

  c. Menstrual phase 

  d. Follicular phase

  a. Cervix

  b. Ovary 

  c. Uterus

  d. Vagina

  a. Carcinoma of the breast

  b. Carcinoma of the cervix

  c. Carcinoma of the uterus

  d. Carcinoma of the ovary

  a. Progesterone   

  b. GnRH  

  c. FSH

  d. Oestrogen 

  a. Merancke  

  b. Menarche 

  c. Mollarche 

  d. Menstarche