Anatomy of male reproductive organs

Question

Answer

What are the three major functions of the male reproductive system?

Production of sperm; production of sex hormones, especially testosterone; maturation and transport of sperm.

Which organs are classified as the external male genital organs in this presentation?

The scrotum, testes, and epididymides.

What is the scrotum?

An outpouching of the lower anterior abdominal wall that extends into the perineum.

Which organs are included among the internal male genital organs?

The vas deferens, seminal vesicles, ejaculatory ducts, prostate gland, and bulbourethral glands.

What structures are contained within the scrotum?

The testes, tunica vaginalis, epididymides, and the lower ends of the vas deferens.

Where is the epididymis located in relation to the testis?

It lies along the posterior aspect of the testis.

What are the three main functions of the epididymis?

It receives sperm from the testis, allows sperm to mature and acquire motility, and stores sperm before transport into the vas deferens.

What is the continuity between the epididymis and vas deferens?

The tail of the epididymis continues directly as the vas deferens.

How many layers make up the scrotal wall?

Six layers.

What is the first layer of the scrotal wall?

Skin.

What are the main characteristics of scrotal skin?

It is thin and wrinkled.

What is the dartos fascia?

A layer of superficial fascia containing dartos smooth muscle.

What abdominal fascial layer is continued as the dartos fascia?

Camper's fascia is replaced by dartos fascia in the scrotum.

What is the function of dartos muscle in temperature regulation?

It contracts in cold conditions to wrinkle the scrotal skin and reduce surface area, and relaxes in warmth to increase surface area.

What happens to scrotal surface area when dartos muscle contracts?

The surface area decreases because the skin becomes more wrinkled.

What happens to scrotal surface area when dartos muscle relaxes?

The surface area increases, allowing greater heat loss.

What is Colles' fascia in the scrotum?

The continuation of Scarpa's fascia into the perineal and scrotal region.

What important structure is formed partly by Colles' fascia?

The median partition of the scrotum, which separates the two testes.

What is the purpose of the scrotal median partition?

It separates the right and left testes.

What is the origin of the external spermatic fascia?

It is derived from the aponeurosis of the external oblique muscle.

What is the origin of the cremasteric fascia and cremaster muscle?

They are derived from the internal oblique muscle.

Which nerve supplies the cremaster muscle?

The genital branch of the genitofemoral nerve.

What is the origin of the internal spermatic fascia?

It is derived from the transversalis fascia.

What are spermatic fasciae?

Fascial coverings formed by the expansion of the distal ends of three abdominal fascial or muscular layers around the spermatic cord and testis.

Why are the testes located in the scrotum rather than the abdominal cavity?

Normal spermatogenesis requires the testes to remain approximately 3 degrees Celsius cooler than core abdominal temperature.

What is the normal temperature relationship between the testes and abdomen?

The testes are maintained about 3 degrees Celsius below abdominal temperature.

Which two muscles help regulate testicular temperature?

The dartos muscle and the cremaster muscle.

What is the response of the dartos and cremaster muscles to cold?

They contract, drawing the testes closer to the body and reducing heat loss.

What is the response of the dartos and cremaster muscles to warmth?

They relax, allowing the testes to descend and increasing heat loss.

What is countercurrent heat exchange in the testes?

Heat transfer between the testicular artery and the surrounding venous blood in the pampiniform plexus.

Which vessels participate in testicular countercurrent heat exchange?

The testicular artery and the veins of the pampiniform plexus.

What is the testis?

A firm, mobile organ within the scrotum that is responsible for spermatogenesis.

How are the testes positioned relative to each other?

The left testis usually lies at a lower level than the right.

Why is the left testis usually lower than the right?

The difference helps reduce compression and prevents the testes from pressing directly against each other.

What is the tunica albuginea?

A tough fibrous capsule that protects and surrounds the testis.

What does the tunica albuginea form inside the testis?

Fibrous septa that divide the testis into lobules.

What covers the anterior and lateral surfaces of the testis externally?

The tunica vaginalis.

What does each testicular lobule contain?

One to three coiled seminiferous tubules.

What is the function of seminiferous tubules?

They are the sites where sperm are produced.

What is the pathway of sperm from the seminiferous tubules?

Seminiferous tubules, rete testis, efferent ductules, epididymal head, epididymal body, epididymal tail, and vas deferens.

What is the rete testis?

A network of channels that receives sperm from the seminiferous tubules and conveys them toward the efferent ductules.

What are efferent ductules?

Ducts that transport sperm from the rete testis to the head of the epididymis.

Which part of the epididymis receives sperm from the efferent ductules?

The head.

Where does most sperm maturation occur?

In the body of the epididymis.

Where is sperm stored before entering the vas deferens?

Primarily in the tail of the epididymis.

What is the tunica vaginalis?

A fluid-filled serous sac surrounding the testis and cushioning it within the scrotum.

What is the embryological origin of the tunica vaginalis?

It develops from an inferior extension of the abdominal peritoneum called the processus vaginalis.

What happens to the processus vaginalis before birth?

It normally closes, leaving the tunica vaginalis around the testis.

Which part of the testis is not covered by the tunica vaginalis?

The posterior border, where structures such as the epididymis and vessels attach.

Why is the posterior border of the testis uncovered by the tunica vaginalis?

It provides an attachment and passage area for the epididymis, vessels, nerves, and duct-related structures.

What is a hydrocele testis?

An excessive accumulation of fluid within the tunica vaginalis around the testis.

When can a hydrocele be congenital or acquired?

It may be congenital or develop later in life.

How may a hydrocele be treated by tapping?

A needle or cannula is inserted through the scrotal skin into the tunica vaginalis cavity to aspirate the fluid.

Which layer is avoided when aspirating a hydrocele?

The visceral layer of the tunica vaginalis covering the testis is avoided.

What is the epididymis?

A highly coiled duct approximately 6 meters long that lies posterior to the testis.

What are the three parts of the epididymis?

The expanded head, the body, and the pointed tail.

Which part of the epididymis is superior?

The expanded head.

Which part of the epididymis is inferior?

The pointed tail.

What is the direct continuation of the epididymal tail?

The vas deferens.

What is the main functional importance of the epididymis?

It is the site of sperm maturation, acquisition of motility, and storage.

Which artery supplies the testis?

The testicular artery.

Where does the testicular artery arise?

Directly from the abdominal aorta.

What is the pampiniform plexus?

A network of veins surrounding the testicular artery and testis.

What does the pampiniform plexus mean linguistically?

Pampinus refers to a tendril, describing the plexus's network-like appearance.

What happens to the pampiniform plexus as it ascends?

It becomes reduced to a single testicular vein.

Where does the testicular vein travel?

It ascends through the inguinal canal.

Where does the right testicular vein drain?

Into the inferior vena cava.

Where does the left testicular vein drain?

Into the left renal vein.

Where does lymph from the testis and epididymis drain?

To the para-aortic lymph nodes.

Why does testicular lymph drain to para-aortic nodes rather than superficial inguinal nodes?

The testes develop high in the posterior abdominal wall, so their lymphatic drainage follows their embryological origin.

What is testicular torsion?

Rotation of the testis around its spermatic cord within the scrotum.

What symptom is strongly associated with testicular torsion?

Sudden severe testicular pain.

Why is testicular torsion a surgical emergency?

Twisting can obstruct venous drainage and later arterial blood supply, causing ischemia and testicular necrosis.

What is the first vascular problem caused by testicular torsion?

Obstruction of venous drainage.

What results from obstruction of venous drainage during torsion?

Edema and hemorrhage within the testis.

What happens if the testicular artery becomes obstructed?

The testicular tissue becomes ischemic, hypoxic, and may undergo necrosis.

How is testicular torsion treated surgically?

The testis is untwisted and then fixed in position to prevent recurrent torsion.

What are seminal vesicles?

Two lobulated glands located at the base of the urinary bladder.

What proportion of seminal fluid is produced by the seminal vesicles?

Approximately 65-70 percent.

What is the approximate length of each seminal vesicle?

About 5 centimeters.

What structure does each seminal vesicle join to form the ejaculatory duct?

It joins the ampulla of the vas deferens.

What is the posterior relation of the seminal vesicles?

The rectum.

What is the anterior relation of the seminal vesicles?

The base of the urinary bladder.

What is the superior relation of the seminal vesicles?

The ureter.

Which arteries supply the seminal vesicles?

The inferior vesical and middle rectal arteries.

What is an ejaculatory duct?

A duct formed by the union of the vas deferens and the duct of a seminal vesicle.

How many ejaculatory ducts are present?

Two, one on each side.

What is the approximate length of an ejaculatory duct?

About 2.5 centimeters.

Where do the ejaculatory ducts pass?

They pass anteroinferiorly through the posterior part of the prostate.

What structure lies between or alongside the ejaculatory ducts within the prostate?

The prostatic utricle.

Where do the ejaculatory ducts open?

They open into the prostatic urethra at the seminal colliculus.

How are the ejaculatory duct openings positioned relative to the prostatic utricle?

They open beside the opening of the prostatic utricle.

What is the prostate gland?

A fibromuscular and glandular organ surrounding the urethra from the bladder neck to the urogenital diaphragm.

What does the prostate surround?

The proximal urethra.

What is the shape of the prostate gland?

It is roughly walnut-shaped, with a superior base and inferior apex.

What is the approximate size of the prostate?

Approximately 3 centimeters long and 4 centimeters wide.

What is the largest male reproductive gland?

The prostate gland.

What does the prostate gland secrete?

A thin, milky, alkaline fluid.

What percentage of seminal fluid is contributed by the prostate?

Approximately 20 percent.