Lecture 1a - male reproductive system Flashcards
Discuss the testis
- The testis is a paired oval shaped gland which is suspended inside a sac-like skin pocket. - is made from the gonadal ridge of the posterior abdominal wall - is retroperitoneal - is a series of tubules
What is the function of the male reproductive system?
is to maintain, transport and nourish sperm
Discuss the anatomical structures associated with the testis
- spermatic cord = suspends testis in scrotum - Scrotum = skin like structue surround the testis seminiferous tubules = avascular part which is the site of sperm production interstitial space = is vascular, is made of Leydig cells, myoid cells, connective tissue elements & blood vessels, lymph vessels and nerves. Its function is hormone prodcuction
What is the pampiniform plexus?
is a series of veins that drain the testis and helps with temperature control of the testis (cools testis a couple of degrees lower than body temp) drains into testicular vein
Describe the innervation of the penis
- sympathetic innervation from T10 which forms the testicular nervous plexus - sensory innervation from L2 (genital branch) of L1&L2 (genitofemoral branch) of the lumbar plexus
Describe the seminiferous tubules
seminiferous tubules = is avascular & site of sperm production (contains a basement membrane, Sertoli cells, germinal epithelium and lumen). Is a series of tubules which are broken into lobules via septae extension of the tunica albuginea and is futher broken into; - tubulus rectus = series of tubules which connect seminiferous tubules to rete testis - Rete Testis = series of tubules which connect tubulus rectus to efferent ductule
What are the connective tissues surrounding the testis called?
- tunica vaginalis = is the outermost connective tissue layer is a remnant of the vaginal process (gubernaculum) - tunica albuginea = innermost layer and has septae extensions whic form the lobes in testis both are from the peritoneum and are dragged down by the testis as they descend
What is the shape of the seminiferous tubules
coiled egg-like shape???
What is the role of Sertoli cells?
Sertoli (sustenticular) cells are exocrine and they aid the nourishment and health of the germ cells. They absorb excess cytomplasm at the end of spermatogenesis from the newly form spermatozoa
What is the role of Leydig cells
Leydig (interstitial) cells are endocrine as they secrete hormones of which include; - testosterone - dehydroepiandrosterone (DHEA) - and Lutenizing hormone when stimulated by the anterior pituitary
Describe the anatomy of the Epididymis cells and what type of epithelium are they.
resembles a comma and comprises of a; - head (caput) = many efferent ductules which connect to the seminiferous tubules via rete testis - body = a single ductus epididymis which is highly coiled - tail (cauda) = poorly developed and is continuous with vas deferens is comprised of psuedostratified coloumnar epithelium which has basal and principle cells. the lamina propria has circular smooth muscle fibres which cause peristalsis which transports the spematozoa towards the ductus vas deferens
What is the role of the basal and principle cells in the epididymis?
principle cells = have motile sterocilia which allows for absorption of excess fluids basal cells = are small round stem cells
Describe the anatomy of the Vas Deferens.
- is a muscular tube, ~45 cm long which passes through the inguinal canal - is composed of psuedostratified columnar epithelium with stereocilia - has a widening, ampulla, when its located behind the urinary bladder - is made of → 1 thick circular layer of smooth muscle → 2 layers of longitudinal muscularis layers
What is the ejaculatory duct?
- is a short, ~2 cm, duct formed by the union of the vas deferens from the seminal vesicles - joins the prostatic urethra - is made of psuedostratified columnar epithelium
- Describe the zones of the urethra.
→ prostatic urethra = first 2-3 cm of urethra which is embedded in the prostate → membranous urethra = 1 cm after prostate near the urethral sphincter → penile urethra = 15 - 20 cm after the sphincter it receives two ducts from the bulbourthral gland is made of transitional and stratified squamous epithelium has dual roles in both urination and the delivery of sperm into the female reproductive tract
What are the tissue types of the urethra?
→ inner epithelial lining (from transitional epithelium, near urinary bladder, to stratified squamous as it reaches external orifice) → a spongy mucosa → a middle smooth muscle layer → other fibroelastic connective tissue layer
What are the accessory glands in the male reproductive system?
- seminal vesicle 2. bulbourethral gland 3. prostate gland
Describe the seminal vesicles and their role:
are paired elongated glands located posterior to the urinary bladder; and is composed of…. - has an extensively folded mucosa to increase surface area - is made of psuedostratified columnar epithelium with well developed rough endoplasmic reticulum for protein secretion - has short, round, basal stem cells - muscularis (an inner circular and outer longitudinal) - fibrous coat its function is to produce ~60% of the semen volume and it; - is a whitish yellow colour - is alkaline to neutralise pH in vaginal canal - has fructose and other sugars - amino acids - prostaglandins to stimulate smooth muscle contraction and uterine contraction - fibrinogen = for the coagulation of semen - ascorbic acid
Describe the bulbourethral gland and their role:
the bulbourethral gland is; - a paired, pea-sized organ within the urogenital diaphragm - is a compoundm, tubuloalveolar gland made of smiple columnar epithelium its function is to secrete; - thick clear alkaline mucus int the urethra - neutralises acidic urine in the urethra - glycoproteins in mucus (pre-seminal fluid) for lubrication
Describe the prostate and its role?
the prostate is a single walnut-sized and shaped organ located inferior to the urinary bladder is made of simple columnar/cuboidal/squamous and spuedostratified epithelium, its function is to secrete; - milky, alkaline fluid ~30% of semen fluid - has clotting enzymes - has prostate specific antigen (marker for prostate cancer) - has prostate acid phosphate - citric acid
Describe the 3 zones of the prostate and what is their significance?
- peripheral zone = close to rectum, 70% glandular tissue and is most susceptible to prostate carcinoma and inflammation, is palpable during rectal exam 2. central zone = 35% glandular tissue, resistant to disease 3. transitional zone = innermost zone that surrounds the urethra, is site of Prostate Benign Hyperplasia (PBH), nodular growth compresses urethra
Describe the anatomy of the penis:
- is a 15 - 20 cm long flexible and spongy organ - is composed of a bulb, crura, body and glans - the body of the penis has 3 different masses of erectile tissue
Label this diagram
- dorsal artery of penis
- cavernous artery
- corpus cavernousum
- glans penis
- corpus spongiosum
- anterior branch of penis
- bulbo-urethral branch
- internal pudendal
What are the main erectile tissues of the penis?
- two dorsal lateral pair = corpus cavernousa which originates from crura
- ventral corpus spnogiosum
Label the following diagram
- anterior blanch
- deep artery
- corpus caverousum
- dorsal artery
- superficial dorsal vein
- deep dorsal vein
- deep fascia
- corpus spongisum
Describe the scrotum:
is a sac of loose skin, fascia and muscles
the muscles include;
- Dartos muscle = is smooth muscle which regulates the temperature of the testis by becoming wrinkled to increase temp or smooth to loose temp
- Cremaster muscle = is skeletal muscle which contractes to raise testis when they’re cold or during ejaculation and relaxes to lower testis when they’re hot
What are the muscles of ejaculation?
- bulbospongiosum muscle = encloses the bulb of the penis and base of corpus spongiosum
- ischiocavernosus muscle = encloses crura of penis or the end of corpus caverosa
What is the role of nitric oxide in the ejaculatory process?
Nitric oxide inhibits the smooth muscle of the corpus cavernousum to allow for vasodilation of the tissue to allow for erection
When does testosterone begin being secreted in fetal males?
the secretion of testosterone begins in about week 8 of gestation when the the SRY gene turns on the expression of testis determining factor which initiates the production of testosterone form the Leydig cells cells in the testis.
How much testosterone do Leydig cells produce daily (average)?
679 ng/dL
What are some common symptoms of low testosterone levels?
erectile dysfunction decreased libido, and reduced bone mass
Briefly explain why mature gametes only carry one set of chromosomes:
Gametes are haploid and only carry half the number of chromosomes a every other cell has. This is because as they combine with another gamete of the opposite sex it forms a new genetically diverse human. This occurs due to the two cellular divisions that gametes undertake first is mitosis then meiosis
Label the following diagram:
- rete testis
- ductus deferens
- body of epididymis
- efferent ductules
- spermatic cord
- cremaster muscle
- tunica vaginalis
- head of epididymis
- lobes of seminiferous tubules
- tunica albuginea
What is the role of the Dartos and Cremastor muscles?
dartos muscle = smooth muscle which becomes wrinkled or smooth to aid in thermoregulation
cremaster muscle = contracts to raise testis upward when they’re cold or during ejaculation and relaxes to lower testis when they’re hot to aid in thermoregulation
Describe the process of spermatogenesis:
Spermatogenesis is the process of sperm cell development. Rounded immature sperm cells undergo successive mitotic and 2 meiotic divisions
- spermatocytogenesis = primitive germ cells, spermatogonia proliferate by mitosis.
- Spermatogonia undergoes mitosis to form 2 identical daughter cells, Spermataogina A and spermatogonia B (both cells are haploid)
- Spermatogonia B differentiates into a primary spermatocyte (haploid cell)
- the primary spermatocyte undergoes meiosis 1 which forms 2 haploid secondary spermatocytes
- the secondary spermatocytes undergo meiosis 2 (which skips prophase 2, which is proliferation) to form 4 haploid spermatids
- spermiogenesis = the maturation of spermatids into spermatozoa
→ acrosome forms from the golgi apperatus and forms around the nucleus
→ flagellum forms
→ mitochondria condense around the mid section
→ cytoplasm is being shed
to produce spermatozoa.
Why is undescended testis a problem and what is this condition called?
cyrotochidism and is when the testis do not descend into the scrotal sac this causes the primordial germ cells to be at body temperature which will denature them and if untreated within the first 3 months after birth the male will be infertile
Describe the structure of a sperm
head = acrosome, nucleus and plasma membrane
mid-piece = centriole and mitochondrial sheath
tail = flagellum and axial filament
What is the acrosome?
is an organelle that forms at the anterior half of the head of a spermatozoa. It is formed from the Golgi apparatus and contains digestive enzymes that enable it to penetrate the membrane of an oocyte
Which part of the male reproductive system is altered during a vasectomy?
vas deferens is tied
What cells are responsible for the blood testis barrier and what is unique about these cells?
is formed by the tight junctions between Sertoli (sustenticular) cells. It means that spermatogozoa and spermatids cannot exit the seminiferous tubules
How does emission take place?
emission is the first stage of ejaculation and is characterised by the movement of sperm from the testis and epididymis to the beginning of the urethra this occurs through peristalsis of the smooth muscle of the vas deferens
The testis are composed of 2 main components, each responsible for a different function either exocrine or endocrine. Fill in the table below:
Names = (a) interstitial tissue (b) seminiferous tubules
Cell types = (a) Sertoli cells (b) Leydig cells
product made = (a) Spermatids (b) Testosterone (androgens)
Label the following diagram
- penis
- corpus cavernousa
- vas deferens
- urinary bladder
- ureter
- seminal vesicle
- rectum
- prostate
- ejaculatory duct
- urinary sphincter
- bulbourethra
- corpus spongiosum
- cremaster muscle
- epididymis
- testis
What is the function of stereocilia in the epididymis?
the stereocilia in the epididymis allow for the absorption of excess fluid and can also phagocytose sperm as well as secretes chemical for sperm maturation
In contrast to the female. The male urethra is long with dual functions. Name these functions
functions both urination of delivery of sperm to the female reproductive tract
What is the clinical significance of the urethra being embedded within the prostate?
due to the urethra being embedded in the prostate dysuria can occur when prostate carcinomas and prostatic benign hyperplasia occurs they expand into the urethra causing it to “shrink” causing discomfort and difficulty whilst urinating
label the zones of the prostate. T= transitional, C= central and P= Peripheral
yellow = central zone
pink = transitional zone
green = peripheral zone
Name structures found within the inguinal canal
the structure found in the inguinal canal are
- spermatic cord
→ cremaster muscle and fascia
→ external and internal spermatic fascia
→ genitofemoral n. sympathetic fibers from T10,
→ testicular a., testicular v., cremaster a.
- ilioinguinal nerve
Name the organs that contribute to semen secretions and summarize each specific contribution:
- Testes
* sperm, ~5% of total semen volume, gametes - Seminal Vesicle
- ~60% of total semen volume, is made of;
- whitish yellow viscous fluid
- alkaline (to neutralise phH of vaginal canal)
- fructose and other simple sugars
- amino acids
- prostaglandins = stimulates smooth muscle contraction and uterine contraction
- fibrinogen = coagulation of semen
- ascorbic acid
- Bulbourethral
- ~ 5% of total semen volume and secretes
- thick, clear, alkaline mucus
- nuetralises acidity in the urethra
- glycoproteins in mucus aid in lubrication
- Prostate
- ~30% of total semen volume and secretes
- milky alkaline fluid
- clotting enzymes
- prostate specific antigen (marker used for prostate cancer)
- prostate acid phosphate (PAP) (another marker)
- citric acid (older marker for prostate cancer)
What is benign prostatic hyperplasia?
is excessive growth of the prostatic tissue that typically occur in the transitional zone of the prostate and occurs in older aged men.
