Lecture 2- The male reproductive system Flashcards
overview of the male reproductive glands
The testes–>spermatic cord –>prostate gland –> urethra
- Testes is connected to the rest of the reproducitive tract by the
vas deferens (ductus deferens)
where does the urethra pass to allow semen to be expelled from the penis
- Urethra passes through the pelvic floor and into the erectile tissue of the penis before the semen is expelled from the penis
microsturcture of the testes ; what is the functional unit of the testes
seminferious tubules (epithelium of the tubules)
- looks like noodles
what occurs in the seminiferous tubules
spermatogenesis
- Compartment of seminiferous tubules are separated by a
capsule (tunica albuginea)
where do seminiferious tubules drain into
efferent ductulus (through the rete testes) into the epididymis (fluid reabsorbed and sperm concentrated)
- Epididymis goes on and form the
vas deferens
- The testes are then also covered by a
serous layer- tunica vaginalis (part of the peritoneum)
Clinical correlate for the Tunica vaginalis-
Hydrocoele
- A cavity which can fill with fluid –> hydrocoele
- Many causes
hydrocele
A hydrocele (HI-droe-seel) is a type of swelling in the scrotum that occurs when fluid collects in the thin sheath surrounding a testicle. Hydrocele is common in newborns and usually disappears without treatment by age 1. Older boys and adult men can develop a hydrocele due to inflammation or injury within the scrotum.
cells of the testes
sertoli and leydig cells
Think of the tests like
spaghetti (seminiferous tubules) bolognaise (interstitial fluid).
Wall of the seminiferous tubules are made up of
Sertoli cells – which support the developing sperm and help them mature- pruning away the cytoplasm
- Sperm comes from the germinal epithelium where the stem cells are found that form the sperm
Interstitial tissue in the testes
- Contains a cell called the
Leydig cell
leydig cells
Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle. They produce testosterone in the presence of luteinizing hormone (LH).
- lots of smooth ER (lipid metabolism)–> testosterone is based around choelsterol which eneds lipid metabolism
blood supply of the testes
- Testes develop in the abdomen and then descend down stretching the neurovascular supply
left and right teste have slighty different blood supply
- Right testicle blood supply
from the right testicular artery and vein (origin = level of renal vesicles
-Left testicles- left testicular vein going into the left renal vein
o Left testes sits lower than the right ( this may be because there is slightly more resistance to the venous drainage on the right than the left)
- While the Testicular vein descends it forms a
plexus - pampiniform plexus around the artery
o Heat exchanged between the vein and artery to keep the testes cool for spermatogenesis
lymphatic drainage of the testes
Different lymphatic drainage of the testis and scrotal skin (important when feeling for lymphadenopathy):
testis lymphatics
- Testis- drain lymph into the para-aortic lymph nodes
scrotal skin lymphatics
- Scrotal skin- drain to the inguinal lymph nodes
Can testicles get twisted?
Yes!
which reflex is used to diagnose testicular tortion
cremastetic reflex
The cremasteric reflex
is performed as part of an evaluation of acute scrotal pain to assess for evidence of testicular torsion. The absence of the reflex is considered to be diagnostic for testicular torsion
testicular tortion is a
surgical emergency
outline testicular tortion
- If the reflexion of the visceral and parietal levels extends up the testis like in Bell-clapper deformity, then it can twist and lead to torsion
- First you get venous drain occlusion
- This causes increase capillary pressure
- Compresses the arteries – cuts off blood supply to testes- ischaemia –> necrosis
why can infertility occur with testicular tortion
Could become infertile- due to the testis having immune privilege (if it becomes necroses the immune system will see the antigens in the necrosed teste and the immune system will start to recognise the other teste (doesn’t happen in everyone)
Can testicles swap sides?
NO
due to scrotal septum
Descent of the testes
Has to get from inside the abdomen to the scrotum – abdomen has a muscular well.
- The gubernaculum is a band that connect the bottom of the scrotum to the bottom of the testis
- Gubernaculum only shortens slightly, but guides the testis down as the rest of the body grows
- The testis do not penetrate the abdominal wall, it invaginates the abdominal wall
- These abdominal muscles become the walls of the spermatic cord, invested in fascia
The spermatic cord has
- Three fascial layers
- External
- Cremasteric
- Internal
external spermatic fascia is
fibrous and derived fromt he external oblique
cremasteric spermatic fascia derived from
internal oblique–>muscle fibres- cremaster muscle
- Cremaster muscle regulates
- the height of where the testis sits
- When cold the cremaster muscle contracts and pulls the testes up
- When hot- relaxed- maximum surface area for heat exchange
- Internal fascia derived from
(fibrous)(transversalis fascia)
- Contents of spermatic cord (rule of 3x blood vessels and 3x nerves X3 other)
Blood vessels
- Testicular artery/ vein (pampiniform plexus
- Cremasteric artery (cremaster muscle)/ vein to cremaster
- Artery to the vas/ vein to the vas
Nerves
- Nerve to the cremaster
- Genital branch of the genitofemoral nerve from the lumbar plexus
- Sympathetic (cause ejaculation of sperm) going to the Vas (sit close to the blood vessels to the vas)
- Ilioinguinal nerve (sits outside the spermatic cord
Other
- Lympathics- to the para-aortic lymph nodes
- The Vas
- Obliterated processes vaginalis
The vas deferens (ductus deferens, Vas) has some important pelvic relations
*
- Important relationship between the Vas and the ureter
- In the male- the ureter passes beneath the Vas (water under the bridge)
- In the female- the ureter passes beneath the uterine artery
the vas takes contirbution from the
sSeminal vesicles to form the ejaculatory ducts (x2) which pass through the prostate gland to the enter the urethra.
- The prostate gland has three important openings
- Urethra hole
- 2x ejaculatory ducts which enter round the back
- If the prostate enlarges then there will be
- compression of the urethra
- lower urinary tract obstruction
…………….. zone of the prostate directly surrounding urethra is most likely to enlarge
transitional zone
- Cancers of the prostate tend to be in the ………………. zone and may not effect urinary flow
peripheral zone
Contributions different glands make to the volume of the ejaculate
- Testes only contribute 10% of volume
- Majority of volume from the seminal vesicle (65%)
- Prostate gland (25%) (prostate massage can cause ejaculation)
- Bulbourethral (Cowpers) gland – 1%
The male urethra and catheterisation
- The male urethra has bends in it- makes passing a catheter hard (easier in females)
- Have to try and straighten the bend
- Straighten the penis
- Gentle tension to the penis will straighten the second bend (if you don’t straighten the penis you can create false entry- make holes in the prostate
- Have to try and straighten the bend
function of the penis
- Expulsion of urine via urethra
- Deposition of sperm in female genital tract
- Removal of competitors sperm
- Attraction of mates
structure of the penis: composed of how many blocks of erectile tissue
3 blocks of erectiel tissue
- X2 ETs eyes are the coprus cavernosum
- ETs mouth is the urethra within the corpus spongiosum
how is an erection achieved
- Vasodilation (esp corpus cavernosum) in penile arterioles and compression of veins results in erection
vasodilatio n is intitated by
parasympathetic stimulation
actual ejaculation is
sympathetic
- Erection is terminated by
vasoconstriction (sympathetic)
penis is anchored to the
pubic symphysis
- Corpora cavernosa is anchored to the pelvis
The penis is homologous to the
clitoris
The tunica albuginea of the penis
- White membrane that surrounds the corpus cavernosum and spongiosum
- Provides the shape of the penis in an erect penis
- Collagen fibres run in both transverse and longitudinal planes- provides support (would be like a slinky if it was just in transverse plan)
Clinical correlation- disruption to the tunica albuginea of the penis
If the tunica albuginea ruptures blood from the corpus cavernosum can spill out and cause dense fibrous scar tissue- cause a bend to occur (surgical emergency)
Blood supply to the penis
*
- Comes from the internal iliac artery- becomes the internal pudendal artery which supplies the arteries to the penis
- Perineal arterial
- Dorsal arteries
- Cavernous artery
- Bulbourethral artery circumflex artery
