Male anatomy Flashcards
What are the components of the male reproductive system?
- Testis
- Epididymis
- Ductus deferens
- Accessory reproductive glands
- Penis
Outline the journey of sperm from production to expulsion
- Made in testis
- Then into epididymis
- Develop functionality
- Travel whole lenght then stored in epididymis
- Then into ductus deferens
- Pelvic urethra
- Accessory glands produce semina plasma
- Mixes with sperm, expelled together as semen
What is the function of the testes?
- Male gonad
- Production of spermatozoa
- Endocrine gland producing testosterone
- Some oestrogen production
Where is the testis located?
In an evagination of the peritoneum called the vaginal tunic
What is the testis covered by? (Going from closest to the testis, moving out)
- Tunica albuginea
- Visceral layer of vaginal tunic
- Parietal layer of vaginal tunic
- Scrotal fascia
- Tunica dartos
- Scrotal skin
What is the vaginal cavity?
- Space between the parietal and visceral layers of vaginal tunic
- Connects directly to the peritoneal cavity
What is the tunica albuginea made up of?
- Covers the testis itself
- Made up of connective tissue (collagen)
- Smooth muscle
What is the scrotum made up of?
- Parietal vaginal tunic
- Scrotal fascia
- Tunica dartos
- Scrotal skin
What cell type is the vaginal tunic made up of?
Peritoneal cells
What are the components of the testis?
- Seminiferous tubules
- Interstitial components
- Mediastinum (connective tissue) with rete testis
What are the components of the seminiferous tubules?
- Tubulus contortus
- Tubulus rectus
Where is the tunica dartos?
- Within scrotal skin
What is the function of the tunica dartos?
- Smooth muscle contraction
- Response to temperature
- Sustain contraction
Describe the role of the scrotal skin in regulation of testicular temperature
- Innervated by sympathetic nerves
- Elevated temp detected by hypothalamus
- Nerve impulse to sweat glands and increase resp rate
What cells are found in the seminiferous tubules?
- Sertoli
- Leydig
What is the function of the seminiferous tubules?
Production of sperm
What is the function of the Leydig cells?
- Steroidogenic
- Produce testosterone
Where are Leydig cells found?
- Interstitial area of seminiferous tubules
- Outside of basal membrane of seminiferous tubules
Where are the sertoli cells located?
Sit on basal membrane
What is the function of the Sertoli cells?
Support germ cels which develop from spermatogona to functional sperm cells
What does the epithelium of testicular lobules consist of?
- Basal compartment
- Adluminal compartment
Describe the transport of spermatocytes from their production site to the epididymis
- Made in tubulus contortus
- Runs into tubulus rectus
- Then into rete testis
- Then run into efferent ducts which run into the epididymis
What are the 3 components of the epididymis?
Head, body and tail
What anatomical features of the epididymis aids the transport of spermatozoa?
- Surrounded by smooth muscle
- Rhythmic contractions transport sperm
What is the function of the epididymis?
- Resorption of fluid
- Secretion of proteins
What is meant by the epididymal transit time?
Time taken for spermatozoa to travel from teh proximal head to the distal tail of the epididymis
What is the specific function of the head and body of the epididymis?
Maturatin of the sperm
What is the function of the tail of the epididymis?
Storage of sperm
What happens in the tail of the epididymis during sexual stimulation?
- Smooth muscles contract
- Spermatozoa transported to ductus deferens
How is a build up of sperm avoided?
- Production does not stop
- Long periods without ejaculation, have contractions moving spermatozoa to ductus deferens
- Then via pelvic urethra to be voided in urine
What is the function of the ductus deferens?
Connection/transport from epididymis tail to pelvic urethra
What allows the ductus deferens to carry out its function?
- Very strong smooth muscle wall
- Propulsion of spermatozoa into pelvic urethra
Describe the path taken by the ductus deferens
From testis through inguinal ring
What structures make up the spermatic cord?
- Ductus deferens
- Testicular artery and vein (pampiniform plexus)
- nerve and lymphatic supply
What surrounds the spermatic cord?
Cremaster muscle
What is the function of the cremaster muscle?
Short term elevation of the testis
What is the function of the pampiniform plexus?
- Heat exchange
- Pulse pressure elimination
- Transfer of testosterone from testicular vein to artey
Describe the anatomy of the pampiniform plexus
- Testicular artery through inguinal canal, highly convoluted
- Tiny venules wrap around it
- Lose heat from artery to cooler venules
What is the pampiniform plexus?
The venous network around the testicular artery
Describe the temperature control using the tunica dartos
- Smooth msucle in scrotal skin
- Contracts (long term) to bring testes to warmer environment
What is the blood supply to the testis?
Right and left testicular arteries
What is the origin of the testicular arteries?
Direct branches of abdominal aorta
What is the venous drainage of the testes?
Right and left testicular veins
Where do the testicular veins open into?
- Right: direct to caudal vena cava
- Left: left renal vein
What are the 5 main pelvic arteries
- External iliac
- Internal iliac
- Coccygeal
- External pudendal
- Internal pudendal
What do the external, internal iliac and coccygeal arteries supply?
Tail
What does the external pudendal artery supply?
Penis
What does the internal pudendal supply?
Connects to dorsal penal artery
What does the internal iliac branch into?
Internal pudendal and prostethic artery
What is the function of the accessory glands?
Production of seminal plasma
- transport medium
Name the accessory glands
- Ampulla
- Vesicular gland
- Prostate gland
- Bulbourethral gland
What are the 2 forms of the prostate gland?
- Body (corpus prostate)
- Disseminate
Describe the locations of the accessory glands
- Ampulls: mucosal growth at end of DD.
- Opens into pelvic urehra
- Budding off these have vesicular glands
- Single opening to pelvic urethra (except boar, separate openings)
What is the colliculus seminalis (CS) in the stallion?
- Opening of ejaculatory ducts
- Common duct of ampulla and vesicular gland
- Open into dorsal aspect of pelvic urethra
What accessory glands are present in the boar?
- No ampulla, all others present
- Large bulbourethral glands
What accessory glands are present in the dog?
- Only ampulla and prostate body
- large prostate
What is unusual about the prostate gland in the dog?
Bilobed and surrounds urethra
What accessory glands are present in the bull?
All (ampulla, vesicular, prostate body and disseminate, bulbourethral)
What accessory glands are present in horses?
Ampulla, vesicular, prostate body, bulbourethral
What accessory glands are present in small ruminants?
Ampulla, vesicular, prostate disseminate, bulbourethral
What accessory glands are present in the cat?
Prostate body and bulbourethral
List different prostate disease in the dog
- Benign prostatic hyperplasia
- Bacterial prostatitis
- Prostatic cysts
What features allow the seminal plasma to carry out its function?
- Fructose as energy source (not stallion)
- May be coagulating
- Buffer
- Prostaglandin
Where is the bulbospongiosus muscle?
Around the bulbourethral glands and penile urethra
What type of muscle fibre is the bulbospongiosus muscle?
Striated
What are the 3 regions of the penis?
- Root
- Body (shaft)
- Glans
What is the root of the penis?
- Paired crura
- Attached to ischiatic arch
- Attachment to skeletal system
What is the function of the ischiocavernosus muscle?
- Pump blood into penis during process of erection
- Encloses the crura penis
What type of muscle fibre is the ischiocavernosus muscle?
Striated
Describe the erectile tissue in the penis
- 3 columns
- Corpus cavernosum x2
- Corpus spongiosum
Describe the corpus cavernosum
- Base of crura
- Main part of corpus
- Surrounded by dense connective tissue (tunica albuginea)
- Filled by blood during erection
Where is the corpus spongiosum?
Around the urethra
What are the 2 types of penis?
- Fibroelastic
- Musculocavernus
What species have a fibroelastic penis?
- Ruminants
- Pigs
Give a basic overview of erection of the fibroelastic penis
- Little increase in length and girth
- Sigmoid flexure stretches when retractor penis muscle relaxes in erection
- Straightens to extend penis
What is a defining feature of the fibroelastic penis?
Fibroelastic tissue in corpus cavernosum
What species have a musculocutaneous penis?
- Horses
- Carnivores
What are the defining features of a musculocutaneous penis?
- More muscular
- Less connective tissue in corpus cavernosum
What is different between erection of a fibroelastic vs a musculocutaneous penis?
- Musculocutaneous has significatn increase in length and girth
- Fibroelastic has little increase in girth and length
What is unusual about the penis in the dog?
Has an os penis
What is the glans penis?
- End of the penis
- Supported only by corpus spongiosum (and os penis in dog)
- Opening of urethra
- Share varies largey between species
What is unusual about the penis of the cat?
- Spines present
- Are androgen dependent
- Thought to stimulate female tract
What is unusual about the glans penis of the boar?
Corkscrew
What is unusual about the ram’s penis?
Urethral process
What is unusual about the stallion glans penis?
- Urethral process
- Fossa glandis around UP
- Urethral sinus dorsal to UP
What stimulates secretion of LH and FSH?
GnRH
What effect does LH have in the male?
Acts on Leydig cells to stimulate production of testosterone
What effect does FSH have in the male?
Stimulates production of inhibin from the Sertoli cells
What is the action of inhibin?
Negative feedback to pituitary to stop the production of FSH
Define the term daily sperm production
The total number of spermatzoa produced per day by both testes
Define the term daily sperm output
The total number of spermatozoa that can be collected over a 24 hour period
What is the volume of semen produced by a bull?
5-8ml
What is the volume of semen produced by a ram?
1.0 (0.5-2.0)ml
What is the volume of semen produced by a stallion?
60ml
What is the volume of semen produced by a boar?
200ml
What is the volume of semen produced by a dog?
2ml (sperm fraction)
What is the volume of semen produced by a tom?
0.01-0.75ml
What factors influence the eididymal transit time?
- Number of ejaculations
- Oxytocin, ACh, prostaglandins and angiotensin II (but unknown why and how)
What factors influence the function of the epididymis?
- Androgen dependent function (androgen suppression leads to impairment of function)
- Maturation of sperm influenced by the production of proteins by the epididymis
List conditions that may result in lower sperm output and reduced fertilisation ability
- Stress
- reduced testosterone production
- Sperm abnormalities
- Pizzle rot
- Cryptorchidism
- Failure of teh accessory glands
- Testicular hypoplasia or neoplasia
- Orchitis
- Urethral stones/blockages
- Temperature
- Over ejaculation
Describe the location of the boar testes
- Peineal
- Horizontal in scrotum
- Closer to body than in bull
- Head of epididymis often lower than tail
What are the boundaries of the inguinal canal?
- Fleshy part of internal oblique on one side
- Pelvic tendon of external oblique aponeurosis on the other
- Entrance: along free caudal edge of internal oblique muscle
- Exit: Between 2 divisionsof external oblique tendon
What is contained in the inguinal canal?
- In both sexes: external pudenal vessels and genitofemoral nerveq
- In males: spermatic cord
- In females: vaginal process (bitch and queen)
Describe the blood supply to the equine penis
- Pudendal artery (normal)
- Obturatory artery (additional)
- External pudendal (additional)
When does testicular descent occur in the bull and ram?
Mid pregnancy
- Confirmed “delayed” at birth
When does testicular descent occur in the boar?
Late pregnancy
- Confirmed “delayed” at birth
When does testicular descent occur in stallions
Late pregnancy/few days after birth
- Confrimed “delayed” around 10 days old
When does testicular descent occur in dogs?
8 days after birth
- Confrimed delayed at 8 weeks
When does testicular descent occur in the tomcat?
2-5 days after birth
- Confirmed delayed at 1 week
What species have sub-inguinal scrotal position?
- Bull
- Ram
What species has a perineal scrotal position?
Boar
What species have an inguinal scrotal position?
- Stallion
- Dog
What species has a sub-anal scrotal position
Tomcat
Which species have a scrotum that is:
a. pendulus
b. compact
c. loose
a. Bull, ram
b. Boar, stallion, tomcat
c. Dog
Which species have vertical testes?
Bull and ram
Which species have horizontal testes?
Boar and stallion
Which species have testes that are horizontal with slight cranio-ventral tilting?
Dog and tomcat
Describe the reproductive anatomy of the male rabbit
- Testes cranial to penis
- Inguinal ring open, so testes can move in and out even when adults
