Testes, Scrotum, Epididymis, Prepuce, Penis, ASG Flashcards
What is the function of testes?
Produce sperm (male gamete) and male reproductive hormones (androgens)
What species have external testes
Domestic mammals including bull ram boar and dog, and also primate
What species have internal testes
Birds, marine mammals, elephant
Explain the functional tissue in the testis: where are sperm produced and where do they exit
Sperm produced in seminiferous lobules (parenchyma) and exit via rete testis/tubules
Three layers of the testis:
Parietal vaginal tunic
Visceral vaginal tunic
Tunica albuginea
Where do the lobules of the testis drain into
Lobules contain seminiferous tubules and drain into the rete testis through straight tubules
What cells are found in the interstitium of the testes
Leydig cells - hormones
Capillaries / endothelial cells
Macrophages (immune cells)
What part of the tubules actually produce sperm?
The seminiferous epithelium within the seminiferous tubules produce sperm, and are surrounded by the peritubular myoid cells.
Rete testes — efferent ducts — epididymis
What is the epididymis and what are the 4 main parts
Sperm travels through the epididymis through to the vas deferens
One continuous tube containing:
- initial segment
- head (caput)
- body (corpus)
- tail (cauda) furthest from efferent ducts
Main functions of the epididymis are
Sperm transport
Sperm storage
Sperm maturation
Absorption of excess rete fluid
2 main ligaments of the epididymis
Ligament of the tail of epididymis — connects the scrotum to the epididymis (tail)
Proper Ligament of the testis — connected the testis to the epididymis (tail)
What does the excurrent duct system contain?
Rete testis — efferent duct — epididymis — vas deferens
What epithelium’s do the efferent duct system contain? What feature helps moves the sperm along?
Cuboidal epithelial cells
Columnar epithelial cells (ciliated)
Ducts are surrounded by smooth muscle
Cilia and smooth muscle help move sperm along ducts
What epithelium does the epididymis have (tall)? What feature helps move the speed along in here?
Contain tall, pseudo-stratified columnar epithelium
Cells have stereocilia to help move the sperm along epididymis
— contain a lot more interstituim than in the testis
Compare the histology of the epididymis to the testis:
Testis:
- epithelium contains lots of round cells
- lined by flat myoid cells
- high density of tubules
Epididymis
- epithelium very rectangular with cilia
- smooth muscle between tubules
- fewer and larger tubules than the testis
What part of the excurrent duct system contains two types of smooth muscle
The Vas deferens
Contains inner circular smooth muscle
And outer longitudinal smooth muscle
Basic functions of the epididymis
Sperm are produced in the testes and stores in the epididymis
1. Storage of sperm
2. Sperm maturation
— mature at different stages
— become fully mature at tail of the epididymis
3. Transport of sperm
Provide more details on the basic functions of the epididymis (3 functions)
Storage
Maturation
Transport
What is the function of the scrotum
— only on external testes not internal testes
— protects the testes and REGULATES TEMPERATURE
What are the 2 major tissue layers of the scrotum
Skin and tunica darts (darts muscle)
What are the 4 layers around the scrotum
External spermatic fascia
Cremaster muscle/fascia
Internal spermatic fascia
Tunica vaginalis (parietal and visceral)
What does scrotal skin contain/what is important about it/what is it’s function??
Regulates testes temperature
Contains thermosensitive nerves and sweat glands to do this
What is the function of the tunica dartos layer
Important for regulating testes temp
— raises testes closer to body
— contraction = scrotal skin wrinkle = heat retained
— relaxation = scrotal skin increases the surface area = heat loss
—Divides the septum into two compartments
What is below the tunica dartos
External scrotal fascia
Cremasteric fascia
Internal scrotal fascia
What is the main vasculature of the scrotum
Blood supply to scrotum via the external and internal arteries/veins
— internal ilia is to posterior scrotal
— external is to anterior scrotal
The 3 major scrotum nerves are
Genitofemoral nerve
Pudendal
Ilioinguinal
What does the genitofemoral nerve innovate
Innervates cranial scrotum and cremaster
What does the pudendal nerve innovate
Innervates caudal scrotum
What does the ilioinguinal nerve Innervates in scrotum
Innervates the dorsal scrotum (outside spermatic cord )
Why is testis temperature important?
Important for sperm production
Must be maintained 4-6 degrees below body temp for sperm to be produced
What happens to testes in the heat?
Sperm Movement and motility, sperm shape and dna damage
Production of sperm can stop at extremely high or prolonged high temperatures
3 control mechanisms of the testes are
Vasculature — heat exchange — external radiant heat loss Musculature — cremaster pumping action on vasculature — dartos muscle - control skin surface area and distance from body Thermoregulatory responses — scrotal sweating — panting/respiratory rate
Vasculature and temperature control of the scrotum; explain how temperature is controlled by vasculature
Close association between testicular artery and pampiniform plexus in the spermatic cord
- creates efficient counter current heat exchange to regulate testicular temperature
- testicular artery highly coiled and superficial on testis = radiant heat loss
What controls temperature regulation in the testes
Arteries and venous blood
Cremaster muscle
How?
- passive heat transfer from artery to veins cools arterial blood and warms venous blood
- cremaster muscle: pumps on vessels, promotes venous return —> enhanced cooling by heat loss from arterial blood
Dartos muscle: actions of the dartos muscle
- controls scrotal skin surface area
- scrotal surface area: relaxed - smooth and contracted = warm
- dartos can lower and raise the testes to lower = cool, and closer to body = warmer
General Thermoregulations of scrotum:
Sweating: localised to scrotum
Panting: triggered if scrotum above 40 degrees
- evaporative heat loss thus decrease temperature
What is the prepuce?
Pouch of skin which ‘Houses’ the glans penis in most species
- has outer parietal layer — continuous with skin
- inner visceral layer — continuous with penis
What is the blood supply to the prepuce
The external pudendal vessels
What is unique about the pig prepuce
There is a preputial diverticulum inside the prepuce of the boar
- gross fluid can contaminate semen in boars = poor ejaculation
Prepuce in horses
Double invagination with prepuce in stallions - forms preputial ring when erect
What are accessory sex glands
Produced fluid; seminal plasma
- secretory tissues along male reproductive tract
What are the four accessory sex glands
- ampullae
- vesicular glands - seminal vesicles
- prostate gland
- bulbourethral gland
What is seminal plasma
- complex transport vehicle
- complex fluid, non cellular part of ejaculate
- semen = sperm plus seminal plasma
What are the functions of seminal plasma
Transport vehicle - sperm to swim Semen coagulation Sperm support - metabolically active cells so need support Regulating sperm maturation Female immune priming
What is the role of seminal plasma on females?
Sperm storage
Ovary; ovulation inducing
Cervix
Uterus
What is the ampulla sex gland
- each vas deferens have thickening of ampulla surround each vas def
- secretions from the ampulla flow directly into the urethra
What are the vesicular glands (seminal vesicles)
Contribute to ejaculation
Paired glands either side of the urethra often conjuring to large volume of ejaculate
The prostate gland
Prostate is a single gland - can be discrete
Between bladder and urethra, embedded in smooth muscle
The bulbourethral glands: function
Produce very thick, viscous secretions
- dense fibrous paired glands
Order of glands from testes to the penis
Ampullae gland - vesicular gland - prostrate gland - bulbourethral gland
Why is there variation in accessory sex glands and why is it important
Presence and a sense of sex glands determine qualities of ejaculate including
- volume
Fractionation (rich or poor quality sperm)
Viscosity - solid substance
What sex glands are present in cattle
All 4 are present in cattle, relatively small bulbourethral glands
What sex glands are present in sheep
4 glands are present, but prostate gland is scattered unlike the bull where the prostate gland is discrete
What sex glands are present in the hors
4 glands present
Large prostate
Large bulbourethral gland
What sex glands are present in the pig
No ampullae
Large bulbourethral glands - very thick/viscous
Sex glands in the dog
Very Large prostate gland
No vesicular or bulbourethral glands
Sex glands in the cat
No ampullae or vesicular glands
But have bulbourethral gland - gets ‘stuck’ when mating
Comparative anatomy summary of accessory sex glands: what species do and don’t have prostate, vesicular, bulbourethral and ampullae
- all have prostate
- carnivores do not have vesicular
- all have bulbourethral except for dog
- pig and cat don’t have ampullae
What is the function of the penis
Delivers semen from the male to female reproductive tract during mating
What are the 3 main parts of the penis
Root
Body
Glands
What is apart of the root penis
- root penis attaches to the Ischial arch
- 3 separate section
- two tapering sections; the crus< and a central bulb
What are the two tissue types in the body of the penis
Corpus cavernous - paired
Corpus spongiosum - surrounds the urethra
Both fill with blood during erection - cause rigid penis
What does the glans penis contain
Contains corpus spongiosum only and urethral opening
- highly sensory - stimulation is a key factor initiating ejaculation
What are the 3 major vessels of the penis
Dorsal artery and vein
Cavernous artery and vein - runs with the corpora **
Bulbourethral artery and vein
What are the 4 main muscles of the penis
Ischiocavernous muscles - help keep blood in the corpora cavernousa
Bulbospongiosus muscles - contract to help empty the urethra
Urethralis muscle - contraction/movement of sperm and seminal plasma to urethra
Retractor penis muscle - contraction and relaxation of the penis
2 main ligaments of the penis
Suspensory ligament - connects to pubic symphysis
Fundiform ligament - connects to the linea alba
What are the two types of penis
Musculocavernous
Fibroelastic
Differences between Musculocavernous penis and Fibroelastic penis
Penis structure in bulls
Have curved glans penis and small urethral process unlike the ram
Sheep penis
Fibroelastic penis
Rounded glands with very long thin urethral process - like a worm
Horse penis structure - what special structure does it have
- large Musculocavernous penis
- diverticulum - accumulates smegma and dead cells/gunk
Pig penis type and shApe
Fibroelastic penis
Glans is corkscrew shaped - has a little lock in feature/hook
Dog penis structure - what is important feature of the dog penis
Bulbus glandis - expands and creates a blockage in female when mating
- stops the penis from exiting when mating (expands)
Pars longa glandis - bone outside of the penis
Cat penis features - what are the spines on the penis dependent on??
Keratinous spines - stimulate females
- androgen dependent - thus not present in castrated males - androgen helps prepare for ejaculation
Which accessory sex gland produced thick, viscous secretions
The bulbourethral sex gland
Which sex gland is described as the thickening of mucosa round vasa deferential, prior to merging at the pelvic urethra
The ampulla, creates a thickening around the vas def
What species has no prostate sex gland
All have a prostate gland
Species that don’t have the bulbourethral sex gland
The dog only
Species that don’t have ampullae sex gland
Pig and cat
Species that don’t have the vesicular gland
Carnivores so dogs and cats
