201 L9 Flashcards
Reproduction
Moving of testes during gestation;
The testes form up in the ——- —— in the upper —— region.
The ——– germ cells are going to become the ——–. They have migrated from the —- —— to the ——- —- at the back of the ——-.
The —————- does not ——– with body growth, so it pulls the ——- down through the —— to the bottom of the —— as the embryo grows.
Towards the end of gestation they will descend through the ——- canal and into the ————.
The testes form up in the gonadal ridges in the upper lumbar region.
The primordial germ cells are going to become the sperm. They have migrated from the yolk sac to the gonadal ridges at the back of the embryo.
The gubernaculum does not elongate with body growth, so it pulls the testes down through the abdomen to the bottom of the pelvis as the embryo grows.
Towards the end of gestation they will descend through the inguinal canal and into the scrotum.
What happens if the tests do not descend?
Does it effect endocrine function?
cryptorchidism (leads to infertility as spermatogensis is stopped).
no
Why are the vas deferens so long even though they have to cover a short distance?
Because the testes at the start are at the back of the embryo and not at the front where they end up the vas deferens have to loop up and over the ureters that are supplying liquid to the kidneys.
The female gubernaculum is an ——– structure that gives rise to the ——– ligaments and is important in ———- development.
The female gubernaculum is an embryonic structure that gives rise to the uterine ligaments and is important in Mullerian development.
MRKH syndrome causes ———– organs.
undeveloped
What controls the movement of testes into the scrotum?
Androgens
What is the most common defect in human males?
Cryptorchidism
Heat exchange system of scrotum;
——- density of ——- glands in the scrotum
The spermatic ——- is coiled in close proximity to the spermatic —— with the ——- blood supply which is returning ——- peripheral blood to the heart
High density of sweat glands in the scrotum
The spermatic artery is coiled in close proximity to the spermatic cord with the venous blood supply which is returning cooled peripheral blood to the heart.
The testes in the scrotum have a temperature __-__ degrees — than the core body temperature.
The effects of ——— can be mimicked by ——– the testes in the scrotum.
The testes in the scrotum have a temperature 4-7 degrees lower than the core body temperature.
The effects of cryptorchidism can be mimicked by warming the testes in the scrotum.
Where are the testes located in adults?
Scrotum
The testes are divided into two separate chambers by the —– —–.
Perineal raphe
What is the function of the cremaster muscle of the scrotum and where is it located?
Lies under the skin of the scrotum and controls the location of the scrotum relative to the body
Contracts in response to cold to draw the testes closer to the body
Each testicle is covered by a ——- sheath called the ——- ———–. This protects the area where ————– takes place.
Each testicle is divided into ——— each of which contains the ——— ———.
Each testicle is covered by a fibrous sheath called the tunica albuginea. This protects the area where spermatogenesis
Each testicle is divided into lobules each of which contains the seminiferous tubules.
Where are sperm formed?
Inside the seminiferous tubules
Briefly describe the steps of spermatogenisis.
The spermatogonia (stem cells) sitting on the basement membrane undergo a series of mitotic divisions.
They then push through into the lumenal compartment and undergo meiosis 1 and 2.
They then undergo cytodifferentiation to elongate and form a sperm
Is spermatogenisis highly regulated?
Yes
How many days does it take for a sperm to be produced from a germ cell in men?
64 days
In men a spermatogenesis cycle starts every —– days
16
What is responsible for the the continuous supply of sperm despite the fact that spermatogenisis takes the same amount of time to be produced?
The spermatogenic wave
What is the spermatogenic wave?
In each segment of a tubule along it’s length spermatogenesis is just ahead of the preceding segment.
How do sperm travel from the testes to the epididymis?
Via the rete testes
What epithelia line the epididymis?
Pseudostratified epithelium
What are the regions of the epididymis and where are they located?
Head (Caput) - top of testes
Body (Corpus) - runs down the side of the testes
Tail (Caudal) - runs from the bottom of the testes to the vas deferens
What is the function of the epididymis?
Site of sperm maturation
Sperm spend about 12 days here
What region of the epididymis is described below?
Receives sperm from the rete testis
Contains many stereocilia
Sperm can not fertilise or move
Caput (head)
What region of the epididymis is described below?
Decreased convolutions and fluid content
Body (corpus)
What region of the epididymis is described below?
Reduced sterocilia
Increased muscularity
Tail (caudal)
Why does the muscularity increase in the caudal region of the epididymis?
Due to the increased viscosity of the fluid
What contributes to the motion in the epididymis?
Fluid flow and peristaltic contractions
At the end of the epididymis do the sperm fertilise and move?
No, but they are capable of both.
The Vas Deferens conduct sperm from the ——— around the ——–, up over the —— and ——-, then back down to join the —– —— via the ———- ——-.
The Vas Deferens conduct sperm from the epididymis around the testes, up over the urethra and bladder, then back down to join the penile urethra via the edjaculatory duct.
What structure is the major site of sperm storage?
Vas Deferens
How long is the Vas Deferen?
45cm
How many layers of muscle does the Vas Deferens have?
Name them in order.
What does this indicate?
3 Layers
Inner longitudinal layer
Middle circular layer
Outer longitudinal layer
Peristalsis
Vas deferens
At the ———- end the lumen is a relatively simple tube.
Just prior to the prostate gland the lumen becomes ——– and ———- with many ——.
This allows additional ——– storage.
This region is called the ——.
At the epididymal end the lumen is a relatively simple tube.
Just prior to the prostate gland the lumen becomes enlarged and folded with many crypts.
This allows additional sperm storage.
This region is called the ampulla.
What happens to the sperm that is produced?
Edjaculation
Loss in the urine
