- Anatomy of the male reproductive system
- Physiology of the male reproductive system
- Common pathologies of the male reproductive system
The male reproductive system consists of the following organs:
- 2 testes (in the scrotum)
- 2 epididymides (in the scrotum)
- 2 deferent ducts (vas deferens)
- 2 spermatic cords
- 2 seminal vesicles
- 2 ejaculatory ducts
- 1 prostate gland
- 1 penis
- The scrotum is a pouch of deeply pigmented skin , fibrous tissue (cremasteric fascia) and smooth muscle (dartos muscle)
- It is divided into two compartments each of which contains one testis, one epididymis and one testicular end of the spermatic cord
- It lies in front of the upper parts of the thighs and behind the penis
- The reproductive glands of the male, equivalent to the ovaries of the female
- Dimensions: 5 cm long x 2.5 cm wide
- Supported in the scrotum by the testicular cord, they are surrounded by three layers of tissues
1. tunica vaginalis:
- outer covering – down growth of the abdominal and pelvic peritoneum
- testes develop in the lumbar region of the abdominal cavity of the foetus, just below the bladder
- they descend into the scrotum and take with them coverings of the epididymis, blood vessels, lymph vessels, nerves and a deferent duct
- the epididymis eventually surrounds the testes in the scrotum and becomes detached
- descent should be complete by the seventh month of foetal life
2. tunica albuginea:
- a fibrous covering surrounding the testes under the tubica vaginalis
- in-growths form septa which divides the glandular structure of the testes into lobules
3. tunica vasculosa:
- a network of blood vessels supported by delicate connective tissue
Structure of the testes
- In each testis there are 200-300 lobules and within each lobule there are 1-3 tightly coiled tubules, called seminiferous tubules
- Between the tubules there are groups of interstitial cells (cells of Leydig) which after puberty secrete the hormone testosterone
- At the upper end of the testis the tubules combine to form a single tortuous tubule – the epididymis which leaves the scrotum as the seminal duct (vas deferens) in the spermatic cord
- Blood and lymph vessels pass to the testes in the spermatic cord
There are 2 spermatic cords, 1 leads from each testis. They consist of:
- 1 testicular artery
- 1 testicular venous plexus
- Lymph vessels
- 1 deferent duct (vas deferens)
The spermatic cord suspends the testis in the scrotal sac and are invested in a sheath of fibrous tissue, connective tissue and smooth muscle. The spermatic cord passes through the inguinal canal
- Branch of the abdominal aorta just below the renal arteries
- Left testicular vein opens into the left renal vein
- Right testicular vein opens into the inferior vena-cava
- 45 cm long
- Passes upwards from the testis through the inguinal canal
- Ascends parallel towards the posterior wall of the bladder where it is joined by the duct from the seminal vesicle to form the ejaculatory duct
- Branches from the 10th and 11th thoracic nerves
Male accessory sex organs
- 2 small fibro-muscular tubules
- Lined with columnar epithelium
- Lying on the posterior aspect of the bladder
- At its lower end its short duct joins with a deferent duct to form an ejaculatory duct
- They secrete and expel a viscous fluid which helps to keep the spermatozoa alive
- neutralizes vaginal acid
- fructose for Adenosine Triphosphate (ATP) production
- prostaglandins stimulate sperm motility & viability
- clotting proteins for coagulation of semen
- About 2 cm long
- Formed by the union of the duct from a seminal vesicle and a deferent duct
- Pass through the prostate gland and join the urethra
- Convey seminal fluid and spermatozoa to the urethra
- Chesnut shaped gland
- Lies in the pelvic cavity, in front of the rectum, behind the symphysis pubis, at the base of the bladder, surrounding the first part of the urethra
- Consists of a fibrous outer layer, a layer of smooth muscle and glandular substance composed of columnar epithelial cells
- Produces a thin lubricating fluid that passes into the urethra through numerous ducts
Bulbourethral gland (Cowper’s gland)
- Secretes alkaline mucous into spongy urethra.
- Neutralizes acids and lubricates.
- The secretions produced by the glands help to protect sperm as it passes through the urethra during ejaculation.
Urethra and penis
Common pathway for the flow of urine and semen, about 20 cm long
Consists of three parts:
- Prostatic urethra
- Membranous urethra
- Spongy/cavernous/penile urethra
- It has a root which lies in the perineum and a body which surrounds the urethra
- It is formed by 3 cylindrical masses of fibrous tissue and involuntary muscle and covered by skin
- It has 2 lateral columns – corpora cavernosa, and one middle column – corpus spongiosum through which runs the urethra
- Its tip is expanded into an acorn-shaped structure – the glans penis just above which is the double fold of skin – the foreskin or prepuce
- Parasympathetic stimulation leads to engorgement of the penis with blood and erection
- Arterial blood is supplied by deep, dorsal and bulbar arteries of the penis
- A series of veins drains the blood into the internal pudendal veins
Follicle stimulating hormone (FSH):
This hormone is synthesized and secreted by gonadotrophs of the anterior pituitary gland. In men, FSH stimulates production of sperm.
Testosterone is a steroid hormone from the androgen group, it is primarily secreted in the testicles of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.
In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle, bone mass, and the growth of body hair
In addition, testosterone is essential for health and well-being as well as the prevention of osteoporosis.
- Anabolic effects include growth of muscle mass and strength, increased bone density and strength, and stimulation of linear growth and bone maturation.
- Androgenic effects include maturation of the sex organs, particularly the penis and the formation of the scrotum in the fetus, and after birth (usually at puberty) a deepening of the voice, growth of the beard and axillary hair. Many of these fall into the category of male secondary sex characteristics.
Inhibin has been defined as a gonadal hormone that exerts a specific negative feedback action on the secretion of FSH from the gonadotropic cells of the pituitary gland. The production of inhibin is stimulated by FSH.
Spermatogenesis is the process by which male primordial germ cells called spermatogonia undergo meiosis
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose, which promote the survival of spermatozoa and provide a medium through which they can move.
- Urethritis: Inflammation of the urethra.
- Penile cancer: Cancer of the penis.
- Undescended testicle: Testis that fails to move into the scrotum as the male foetus develops.
- Torsion of the testicle: The spermatic cord that provides the blood supply to a testicle is twisted, cutting off the blood supply.
- Hydrocele: The accumulation of serous fluid.
- Epididymitis: Painful inflammation of the epididymis.
- Variocele: An abnormal enlargement of the pampiniform venous plexus in the scrotum.
- Testicular neoplasia: Tumour of the testicle.
- Seminoma: Malignant tumour of the testis; usually occurring in older men.
- Teratoma: An encapsulated tumour composed of tissues not normally present at the site.
- Prostatism: Symptoms of frequency, nocturia, urgency, hesitancy, a poor stream, and post-micturition dribbling.
- Prostate cancer: Cancer of the prostate.