Test 2- Colombo - Male Repro Flashcards
The sperm cell is what?
Haploid flagellated cell with a head and a tail. Head delivers DNA, tail does the locomotion.
The head of the sperm contains genetic info and the _____________.
Acrosome
The acrosome is a vehicle full of enzymes which can break down what, and it is called what?
The outer layer of the ovum
Acrosome rxn
What are the centrioles in a sperm cell formed from?
A complex of microtubules. The centriole is delivered to the ovum w/ genetic material to form a centrosome and are involved int he initial zygotic divisions.
What is the axoneme?
The cytoskeletal component of the flagella formed from microtubules (made of tubulin)
*This is the engine room of the sperm. It is packed with MITOCHONDRIA. Max velocity: 1-4mm/min.
What is on the cell membrane of sperm that give it a sense of direction and what is this called?
Chemotactic sensors
Gradient sensing
Spermatogenesis begins around what age?
13
What starts the process of spermatogenesis?
LH and FSH released from the Ant Pit. This continues thruout life.
Where are sperm produced?
In the testes, packed with could seminiferous tubules. These tubules are lined with spermatogonia.
What are spermatogonia?
Germinal epithelial cells
What surrounds the spermatogonia?
Large Sertoli cells
What do Sertoli cells do?
They act like nurses to the developing sperm. They supply nutrients, moving the differentiating cells, and FORMING THE BLOOD-TESTIS BARRIER (Sertoli Cell Barrier).
Why is the Sertoli Cell Barrier important?
If blood saw sperm, it would attack auto-immunly. Due to this, the testes are said to be immunologically privileged.
What do the Leydig cells do?
Produce testosterone
What tells the Leydig cells to produce testosterone?
LH - This initiates puberty and spermatogenesis
Tell me the pathway of cells in spermatogenesis.
Spermatogonia (D)> Primary Spermatocyte (D) {This is the mitotic division}> 2 Secondary Spermatocytes (Each are [H]){This is the first meiotic division}> 4 Spermatids (H){This is the second meiotic division}> 4 Sperm cells (H) {Tails added. No division}
How does the sperm cell get to the seminiferous tubule?
Once there, is the sperm cell motile?
The tail is added to the spermatid. The tail then decouples from the Sertoli cell. The sperm cell enters into the seminiferous tubule.
It is NOT motile.
How is spermatogenesis hormonally controlled?
GnRH stims Ant Pit to release LH, FSH, and GH.
LH stims Leydig cells to make testosterone. Testosterone then drives spermatogenesis division.
FSH stims Sertoli cells. Estrogens formed from testosterone regulate spermatogenesis.
GH does a basic total regulation of testes metabolism.
This process is inhibited by inhibin. Inhibin is produced by Sertoli cells. This negatively feedbacks in excess FSH secretion
How does a sperm cell get from the seminiferous tubules to the ductus (vas) deferens?
Seminiferous tubules>tubulus rectus>rete testis>epididymis>ductus deferens
What does the rete testis do?
It is a net-like structure that delivers maturing sperm to epididymis AND reabsorbs some tubular fluid. This concentrates the sperm cells.
How many mature sperm are produced per day, and how long are they typically stored in ductus?
120 Million
About a month
What does a vasectomy do?
Obstructs ductus. Prevents sperm from entering into semen.
Why do the testes hang down from the body?
Spermatogenesis is most efficient at just below body temp.
What do the seminal vesicles release, what do those secretions do, and how much of a percentage of semen is their secretion?
Fructose - Fuel for sperm motility
Prostaglandins - Thins cervical mucus, possibly causes propulsion inwards
Fibrinogen - This can be cleaved to form a clot later on.
60-70%
What are the seminal vesicles lined with?
Secretory epithelium - it secretes mucus
What secretions does the prostate add to the semen, what do those secretions do, and how much of the semen is it?
Clotting enzymes - causes semen to clot slightly - “keeping it in place”
Profibrinolysin - helps to breakdown the clot that semen forms
Alkaloids - sperm do better at a more neutral pH. Optimal pH - around 6.5
25-30%
What do the bulbourethral glands do?
What percentage of ejaculate do they contribute to?
Produce a mucus-like secretion that forms the pre-ejaculate and lubricates and cleanses the urethra.
*This secretion can contain sperm from prior ejaculations, but more importantly, this fluid can transmit infectious agents in the pre-ejaculate.
1%
The finished product of semen is what pH?
7.5
What does the semen do around the cervix?
Forms a weak clot that gradually degrades after about 20 minutes
How long can sperm survive in utero?
2-3 days
What is sperm capacitation?
Semen contains a number of mobility inhibition factors to keep the sperm in “stasis” and once in the vagina, the inhibition factors are “capacitated” or washed away. Once this occurs, sperm becomes fully motile.
The cell membrane around the acrosome weakens, allowing easier rupture
Ca2+ permeability increases which causes more vigorous motion in the flagella
What three things cause vasodilation of the penis?
Ach, NO, and vasoactive transmitters
T/F - STDs can be transmitted in the ejaculate.
True
