Male Reproductive System
Structural Plan:
Essential organs of reproduction are the gonads (testes), which produce sex cells (sperm)
Accessory organs of reproduction include:
Ducts: passageways that carry sperm from testes to the exterior of the body
Sex glands produce protective and nutrient solution for sperm
External genitals: scrotum and penis
Testes: the gonads of men
Structure and Function
Testes are located in the scrotum, so that the testes are kept at a lower temperature than the core of
the body
Spermatogenesis is the process of sperm production
The head of the sperm contains genetic material
The acrosome contains enzymes to assist sperm in penetration of the ovum
The mitochondria provide energy for movement
Production of testosterone
Testosterone “masculinizes” and promotes the development of male accessory organs; stimulates
protein anabolism and development of muscle strength
Male Reproductive System
Reproductive ducts: ducts through which sperm pass after exiting the testes until they exit from the
body
Epididymis: a single, coiled tube about six metres in length; it lays along the top and behind the testis in
the scrotum
Sperm mature and develop the capacity for motility as they pass through the epididymis
Epididymitis is painful inflammation of the epididymis
The ductus (vas) deferens receives sperm from the epididymis and transports them from the scrotal sac
through the abdominal cavity
Male Reproductive System
Semen: a mixture of sperm and secretions of the accessory sex glands; averages three to five milliliters
per ejaculation, with each milliliter containing about 100 million sperm
Seminal vesicles
Pouchlike glands that produce about 60% of seminal fluid volume
Secretion is yellowish, thick, and rich in fructose to provide the energy needed by sperm for motility
Prostate gland
Shaped like a doughnut and located below the bladder
The urethra passes through this gland
Its secretion, representing about 30% of seminal fluid volume, is thin and milk-colored; it activates
sperm and is needed for ongoing sperm motility
Bulbourethral (Cowper’s) glands
These glands resemble peas in size and shape
They secrete a lubricating, mucus-like fluid constituting less than 5% of seminal fluid volume
External genitals
The penis and scrotum are collectively referred to as the genitalia
The penis has three columns of erectile tissue: two dorsal columns called corpora cavernosa, and one
ventral column, called the corpus spongiosum, which surrounds the urethra
The glans penis is normally covered by foreskin
Surgical removal of the foreskin is called circumcision
Disorders of the Male Reproductive System
Disorders of the testes may cause reduced reproductive ability (infertility) or total inability to reproduce
(sterility)
Oligospermia refers to low sperm production
Cryptorchidism involves undescended testes
Testicular cancer is most common in young adult men aged 25 to 35 years
Disorders of the
Male Reproductive System
Disorders of the prostate
Benign prostatic hypertrophy: enlargement of the prostate common in older men
Prostate cancer is a leading cause of cancer deaths in men over the age of 50
Disorders of the penis and scrotum
Phimosis: tight foreskin that cannot be retracted over glans
Paraphimosis: foreskin that cannot be replaced to its usual position after it has been retracted behind
the glans
Impotence: failure to achieve erection of the penis (“erectile dysfunction”)
Hydrocele: an accumulation of watery fluid in the scrotum
Inguinal hernia: protrusion of the abdominopelvic organs, possibly into the scrotum
Hypospadias: the urethra opens on the underside of the glans or shaft of the penis
Epispadias: the urethra opens on top of the glans or shaft of the penis
Female Reproductive System
Structural plan—organs classified as essential or accessory
Essential organs are the gonads (ovaries), which produce sex cells (ova)
Accessory organs of reproduction
Ducts or modified ducts—including the oviducts, uterus, and vagina
Sex glands—including those in the breasts
External genitals (vulva)
Female Reproductive System
Ovaries
Structure and location
Paired glands weighing about 3g each, resembling large almonds in shape and size
Attached to ligaments in the pelvic cavity on each side of uterus
Microscopic structure
Ovarian follicles—contain oocytes (immature sex cells; about 1,000,000 at birth)
Primary follicles—about 400,000 at puberty
About 350 to 500 mature follicles ovulate during the reproductive lifetime of most women
Functions
Oogenesis—cell division produces daughter cells with equal chromosome numbers (23) but unequal
cytoplasm. Ovum is large; polar bodies are small and degenerate
Production of estrogen and progesterone
Estrogen causes development and maintenance of secondary sex characteristics
Progesterone stimulates secretory activity of uterine epithelium and assists estrogen in initiating menses
Reproductive ducts
Uterine (fallopian) tubes
Extend about 10 cm from the uterus into the abdominal cavity
The expanded distal ends are surrounded by fimbriae
Surgical removal of the ovaries is called oophorectomy
Uterus—composed of body, fundus, and cervix
Lies in the pelvic cavity, just behind urinary bladder
Myometrium is the muscle layer
The endometrium lost in menstruation
Menopause: End of repetitive menstrual cycles (at about 45 to 50 years of age)
Surgical removal of the uterus is called hysterectomy
Vagina
A distensible tube about 10 cm in length
Located in the pelvis, between the urinary bladder and the rectum
Female Reproductive System
Accessory or supportive sex glands
Bartholin’s (greater vestibular) glands
Secrete a mucus-like lubricating fluid
Their ducts open between the labia minora
Breasts
Located over the pectoral muscles of the thorax
Size is determined by fat quantity more than by amount of glandular (milk-secreting) tissue
Lactiferous ducts drain at the nipples, which are surrounded by the pigmented areola
Lymphatic drainage is important in the spread of cancer cells to other parts of the body
External genitals
Include mons pubis, clitoris, orifice of urethra, Bartholin’s gland, vagina, labia minora and majora, and
hymen
Perineum: the area between the vaginal opening and anus
Disorders of the Female Reproductive System
Hormonal and menstrual disorders
Menstrual cramps or dysmenorrhea: painful menstruation
Amenorrhea: absence of normal menstruation
Dysfunctional uterine bleeding (DUB): irregular or excessive bleeding resulting from a hormonal
imbalance
Premenstrual syndrome (PMS): a collection of symptoms that occur in some women before
menstruation
Infection and inflammation
Exogenous infections are often sexually transmitted; endogenous infections are caused by organisms
already in or on the body
Pelvic inflammatory disease (PID): an acute inflammatory condition of the uterus, uterine tubes, or
ovaries caused by infection
Vaginitis: an infection of the vaginal lining, most often resulting from STDs or yeast infections
Disorders of the Female Reproductive System
Tumors and related conditions
Myoma or fibroids: benign tumors of the uterus
Ovarian cysts: fluid-filled enlargements; usually benign
Endometriosis: presence of functioning endometrial tissue outside the uterus
Breast cancer is the most common type of cancer in women
Ovarian cancer can result from metastasis of breast cancer or can arise independently
Cervical cancer is often detected by a PAP smear
Infertility can result from factors such as infection and inflammation, tumors, and hormonal imbalances