Session 1: The Male Reproductive System Flashcards
Where can the testes be found?
In the scrotum
Optimum temperature for spermatogenesis.
Slightly cooler than core body temp
Blood supply of testes
Testicular artery
Testicular artery is a branch of what?
Abdominal aorta
Venous drainage of the testes.
Pampiniform plexus
Layout of the pampiniform plexus.
It surrounds the testicular artery which is thought to cool down the blood.
It then forms the left and right testicular veins.
What do the left and right testicular veins drain into?
Right drains straight into the IVC.
Left drains into the left renal vein before draining into IVC.
What happens if the pampiniform venous complex is obstructed? Like due to intra-abdominal pathology or renal pathology.
It can enlarge and lead to a varicocoele (varicose vein of the testis).
What is testicular torsion?
When the spermatic cord of the testis twists on itself.
Complications of testicular torsion.
If blood supply is restricted it can lead to ischaemia and loss of a testis.
Most common testis for testicular torsion.
Left.
Lympathic drainage of the testes. Why is this important to consider?
Para-aortic lymph nodes. In case of testicular malignancy we need to know how it will spread.
Lympathic drainage of the scrotum.
More superficially via inguinal lymph nodes.
Where in the testes does spermatogenesis occur?
In the seminiferous tubules of the testes.
What cells do seminiferous tubules consist of?
Sertoli cells
Leydig cells
Function of sertoli cells.
Spermatogenesis
Support developing sperm by extruding cytoplasm from the sperm in order for it to swim better
Function of leydic cells.
Production of testosterone.
Where do the seminiferous tubules run and form?
They come together at the rete of testis and join the epididymis.
Main role of epididymis.
Sperm maturation.
What is the epididymis continuous with?
The vas deferens (ductus deferens)
What does the vas deferens travel through?
The spermatic cord.
The spermatic duct joins a duct somewhere on its journey out. Which?
The ejaculatory duct at the prostate.
In relation to the spermatic cord, where does the ureter pass?
Underneath the vas deferens.
What does the spermatic cord contain?
3 fascial layers 3 arteries 3 veins 3 nerves The vas deferens
Accessory glands of the spermatic cord.
Seminal vesicles
The prostate
Bulbourethral glands
Main function of the seminal vesicles.
The seminal vesicles produce a fructose-based alkaline fluid which approximately 65% of the ejaculate consist of.
This fluid gives nutrients to the sperm and also neutralises the acidic environment of the vagina in order for the sperm to survive.
Main function of the prostate gland.
Produce a milky secretion which makes up about 25% of the ejaculate. It contains proteolytic enzymes and is slightly acidic.
Main function of the bulbourethral gland (also called Cowper’s gland).
Produce a secretion that will reduce friction of the ejaculate. Also reduce acidity.
It only makes up a small percentage of ejaculate.
There are two tissues of the penis. Which?
Corpus spongiosum
Corpus cavernosum
Features of the corpus spongiosum.
Expansile tissue through which the urethra travels. It stays patent for the passage of sperm during ejaculation.
Features of the corpus cavernosum.
Paired tissue. Main erectile tissue of the penis.
This tissue is attached to bone in order to help anchor the penis.
What is hydrocoele?
Accumulation of fluid around the testis. (Pathological)
In the tunica vaginalis.
Why can’t the testes swap sides?
The testes evaginate the abdominal wall as they are pulled through the gubernaculum. This forms a spermatic fascia around each testis and its vessels.
Physiological cause of an erection.
Vasodilation of penile arterioles and compression of veins.
What physiological reaction causes the vasodilation of penile arterioles?
Parasympathetic stimulus.
What is an erection terminated by?
Sympathetic response causing vasoconstriction.
Which nervous system is mainly responsible for ejaculation?
Sympathetic nervous system.
What is the tunica albuginea of the penis?
Connective tissue enveloping the corpus cavernosa but also the corpus spongiosum.
Keeps the internal structure of the testis as well compartmentalising seminiferous tubules.
How are the collagen fibres arranged in the tunica albuginea?
At right angles to each other (perpendicular).
On circumferential and one that goes parallel to the penile long axis.
Briefly explain the inguinal canal.
In order to descend, the testes took layers of the abdominal wall to form the inguinal canal. This is a common point of hernias.
What is the tunica vaginalis?
As the testes descend they will take some peritoneum with them which envelopes the testes. This is the tunica vaginalis.
What happens if the tunica vaginalis fills with fluid?
It leads to a hydrocoele.
The three fascias of the spermatic cord.
Internal spermatic fascia
Cremasteric fascia
External spermatic fascia
What is the internal spermatic fascia derived from?
Transversalis fascia (of transversalis abdominis)
What is the cremasteric fascia derived from?
Investing fascia of both superficial and deep surfaces of the internal oblique fascia
What is the external spermatic fascia derived from?
From the external oblique aponeurosis and its investing fascia.
How do the testes and spermatic cord end up invested in those three fascial layers?
Because as the testes are pulled down via the gubernaculum it is pulled through the abdominal wall and becomes invested in the fascial layers of the abdominal wall muscles.
What is the gubernaculum?
An embryonic structure (two of them) attaching to the caudal end of the testes. It is also called the caudal genital ligament.
The upper part of the gubernaculum will degenerate.
Will the entire gubernaculum degenerate?
No, the lower part will persist as the scrotal ligament (gubernaculum testis).
Purpose of the scrotal ligament.
Secures the testes to the most inferior portion of the scrotum and tethering them in place.
This means that the testes can’t move completely freely.
Where will you find a prostate malignancy?
In the peripheral zone of the prostate gland.
Where will you most likely find BPH (benign prostatic hyperplasia)?
In the transitional zone
Lymphatic drainage of the testes.
Para-aortic lymph nodes
Lymphatic drainage of the scrotum
Superficial inguinal lymph nodes.
Venous drainage of the scrotum.
Anteriorly: external pudendal veins
Posteriorly: Posterior scrotal branches of the perineal vessels
Venous drainage of the prostate gland?
Prostatic venous plexus draining into the internal iliac vein.
Lymphatic drainage of the prostate gland.
Mainly: obturator and internal iliac lymphatic channels
To a lesser extent: external iliac, sacral and para-aortic lymph nodes
Coverings of the testes and scrotum. (Superficial to deep)
Skin
Subcutaneous tissue called dartos fascia and dartos muscle
External spermatic fascia
Cremaster muscle
Cremasteric fascia
Internal spermatic fascia
Tunica vaginalis (parietal and visceral layers)
Coverings of the spermatic cord
External spermatic fascia
Cremasteric fascia and cremaster muscle
Internal spermatic fascia
What is the tunica albuginea?
A fibrous connective tissue layer enveloping both the corpus spongiosum and the corpus cavernosum.
Also supports the internal structure of the testis as a capsule.
Examples of painful scrotal lumps.
Torsion of testis Torsion of testicular or epididymal appendages Strangulated inguinal hernia Haematocoele Epididymis-orchitis
Painless scrotal swellings
Hydrocoele Epididymal cyst Spermatocoele Varicocoele Testicular tumour
In very gerneral terms, how may you discriminate between a hernia and a swelling associated with the testis?
Hernias (and varicocoeles) are more prominent when a patient is standing up.
What veins are affected in a varicocoele?
The pampiniform venous plexus.
Is a varicocoele more common on the left or right?
On the left
Why is a varicocoele more common on the left?
Because from the pampiniform venous plexus which drain into left and right testicular veins. The right will drain into IVC directly whereas the left will first drain into left renal vein and then IVC
This means that the left venous drainage have higher venous resistance than the right.
In relation to veins and arteries, how are the testis kept cool?
The testicular artery and testicular vein are intertwined in order to make the vein cool down the blood of the artery.
Optimum spermatogenesis temperature is also achieved by the testis being “outside” of the body.
Complications of BPH.
Compression of urethra as urethra passes through the transitional zone.
Blood supply of the penis
Internal iliac artery goes to internal pudendal artery to dorsal arteries
