Male repro Flashcards
Is the epididymis a paired organ?
Yes
Where are the testes located?
Usually within the scrotum
Male reproductive system consists of?
Testes Epididymis Deferent duct Urethra Accessory sex glands Penis
When does the male reproductive system switch from paired to unpaired?
After deferent duct (urethra)
3 components of the fibrous skeleton of the testes?
- External tunica albuginea
- Central rod of tissue - the mediastinum
- A series of fine lamellae, the septula testis - radiate out of the mediastinum to blend with tunica albuginea - resulting in division f testicular parenchyma into seperate wedge like testicular lobules
Seminiferous tubules
Part of testicular parenchyma
Highly convoluted tubules - open at each end into a terminal straight portion
2 types of epithelial cells lining seminiferous tubules?
- Sustentacular/ Serotoli cells - tall columnar cells - support for spermatogenic cells
- Spermatogenic cells - mature to become sperm cells
Sperm maturation
They begin peripherally in the epithelium as spermatogonia, which divide by mitosis to become primary spermatocytes, which divide by meiosis I into secondary spermatocytes, which divide by meiosis II into spermatids, which then undergo maturation without further division to become spermatozoa
As the spermatogenic cells divide and mature, they are pushed from the base of the epithelium towards the lumen of the tubule, ascending along the sides of the sustentacular cells
Ultimately, spermatozoa are released from the terminal ends of the sustentacular cells (spermiation) and float free in a small amount of liquid in the lumen of the seminiferous tubules (spermatozoa is not motile at this stage)
Spermatozoa in the seminiferous tubules by contraction of the peritubular cells move towards the straight terminal portions of the tubules
From here, the spermatozoa pass into a network of microscopic channels within the mediastinum, the rete testis
They trickle along these channels towards the end of the testis
From here, the spermatozoa enter efferent ductules, which exit the testis by passing through the tunica albuginea
The whole process of spermatogenesis can be divided into:
Spermatocytogenesis
Meiosis I & II
Spermiogenesis (cell maturation without division)
How are sperm transported along seminiferous tubule?
Peritubular contractile cells that surround the seminferous tubule
What do interstitial cells between seminferous tubules produce?
Male hormones - such as testosterone
Efferent ductules combine to form?
A single, long epididymal duct
The epididymis containing the epididymal duct can be divided into 3 segments?
- The head - marks the end where the efferent ductules come together to form the epididymal duct and is firmly anchored to the testis by these ductules.
- The body
- The tail - Opposite end to the head, the tail of the epididymis, the epididymis is again anchored to the testis by a short connective tissue cord, the proper ligament of the testis
Why is the head of the epididymis large?
There is a lot of efferent ductules there
Why is the tail of the epididymis large?
Acts as a storage centre for sperm
Are the sperm motile during their passage through the efferent ductules and epididymal duct?
No, transport through the system is via cilia in the epithelial cells lining the efferent ductules, and then via contractile cells surrounding the epididymal duct
Is the passage of sperm through the epididymal duct slow or fast?
Slow, epididymal duct is very long - during this slow passage excess fluid is absorbed by the epididymis
When do sperm become functionally fertile and motile?
When they loose the residual cytoplasmic droplet
After the epididymis where do the sperm travel?
Deferent ducts
What is the role of the deferent ducts?
To rapidly transport sperm from the tail of the epididymis to the urethra - during ejaculation
- to do this it has a very thick muscular wall & is a straight tubule unlike the convoluted epididymis
How is sperm loss from the epididymis reduced outside of ejaculation periods?
The muscle of the deferent ducts is contracted, reducing sperm loss from the tail of the epididymis
Some sperm is still lost due to lack of sphincters in male repro tract
What is the vaginal process?
Peritoneal pouch in which the each testis lies and is continuous with the peritoneum lining the abdominal cavity
What is the peritoneal fold suspending each testis called
Mesorchium
What is the spermatic cord?
The combination of the mesorchium, the vessels and nerves contained in its edge, the ductus deferens, its own mesoductus, the whole lot surrounded by the vaginal process of peritoneum, and passing through the inguinal canal and heading to the scrotum, is the spermatic cord
Also associated with the spermatic cord, but external to the peritoneum of the vaginal process, is a strip of skeletal muscle, the external cremaster muscle
Scotum
a double skin pouch, created simultaneously by left and right gubernacula, the wall of the scrotum is complex – involving both features of skin and those of peritoneum
Layers of the scrotum (externally to internally)
- Epidermis & dermis
- Tunica dartos - a layer of smooth muscle
- Multiple layers of fascia - spermatic fascia
- Peritoneum of the vaginal tunic
Separation between the left and right vaginal processes within the scrotum is due to
Spermatic fascia
What are the mechanisms of the testes for temperature regulation?
- Blood supply and drainage - testicular arteries supply warm blood - become enclosed by dense network of veins - heat transferred from artery to veins (leaving testes) - cool blood reaches the testes
- Movement of the testes – muscles contract to pull testes towards the body (warming it) or allow gravity to take effect and let the scrotum fall away from the body (cooling it)
- Evaporative cooling - thin skin with sparse hair allows for cooling - evaporation secretions from sweat glands in the skin of the scrotum provide further cooling
Mammals with the testes still inside the body cavity are described as
Testicond
Four potential glands that contribute to the fluid of the ejaculate
- Ampullary glands
- Vesicular glands
- Prostate
- Bulbourethral glands
Location of Ampullary glands
In the wall of the terminal ends of the deferent ducts
Ampullary glands are well developed in which species?
Stallion & ruminants
Vesicular glands are well developed in which species?
Ruminants, horse, pig
Absent in carnivores
Vesicular glands are absent in what animal species?
Carnivores
2 forms of the prostate?
- Disseminate prostate - Within the wall of the urethra, many small glands opening independently along the length of the pelvic urethra - deep in urethral musculature
- Compact prostate - A compact mass of glands associated with the cranial part of the urethra, - external to urethral musculature
Which animals have a prostate mostly or completely of the compact form?
Horse & carnivores
Which of the accessory sex glands is located most caudally?
Bulbourethral gland
Are bulbourethral glands paired or unpaired?
Paired
In what animal are the bulbourethral glands largest?
Boar
Secretions are thick and sticky (viscous) are are used to seal the sow’s cervix after ejaculation - reducing sperm leakage and preventing subsequent matings from other males
The penis consists of three erectile tissue rods:
Two corpora cavernosa - connected to skeleton, form an anchoring point to assist with pushing into female reproductive tract
An unpaired corpus spongiosum
What is primarily responsible for creating the increase in length and rigidity of the penis during erection
The two corpora cavernosa
Os penis
When the cranial end of the corpora cavernosa is replaced by bone
How does erection of the corpora cavernosa happen?
Combination of increased arterial flow into them, and decreased venous outflow
How does the corpus cavernosa cope with high blood pressure during erection?
Each corpus cavernosa is surrounded by a thick dense connective tissue capsule - the tunica albuginea
Musculocavernous type of penis
Filling of the corpora cavernosa results in great swelling both in length and diameter
- the horse has this type of penis
Fibroeleastic penis
Is there is relatively little space inside the corpora cavernosa, and relatively little swelling is possible In this form of penis, the apparent increase in length of the penis during erection is mostly due to straightening of a bend (a sigmoid flexure) within the body of the penis
- seen in the pig and ruminants
What forms the bulb of the penis?
corpus spongiosum
The glans penis
terminal enlargement at the cranial end of the penis which provides both padding/protection for the female vagina during copulation, and helps to seal the vagina during ejaculation, to reduce ejaculate loss
Stallion glans penis
The glans penis takes the form of a conical cap over the corpora cavernosa
Tomcat glans penis
is a long conical structure covered with spines, that help to stimulate the cervix of the queen, facilitating ovulation in this species.
Has very short penis
Glans penis in ruminants
glans is relatively small, and asymmetrically positioned – it does not cover the apex of the corpora cavernosa
Boar penis
There is essentially no glans in the boar. Instead, the enlargement of the terminal end of the penis is produced by spiraling of the apex of the penis, into a corkscrew shape
Prepuce
Skin pouch that covers the apex of the penis