Fertilisation journey Flashcards
During what some key molecular changes occur?
The sperms journey through the reproductive tract.
Why do the sperms go through a journey through the reproductive tract?
In order to become fertilisation competent.
Where are sperms restored with successful spermatogenesis?
In the epididymis.
Until when are the sperms restored in the epididymis?
Ejaculation.
Die.
From what must the sperms release themselves?
The semen.
What must the sperms begin to do after they release themselves from the semen?
The challenging journey of navigating the female tract.
Why do sperms must begin the journey of navigating the female tract?
To find the egg.
How many eggs can be successful?
1.
How does the massive rubbing rate going?
From hundreds of millions in the vagina to just a few in the upper tract.
What does each part of the tract represent?
Its own challenges.
Why are the sperms specially designed?
To overcome their challenges in the co-evolution process.
How many excess phenomenon are observed in vitro?
3.
Why are the three excess phenomenon in vitro proposed?
To facilitate sperm journey to the egg.
What might exist along the tubule?
A temperature gradient.
What might the sperm do in response to a temperature gradient?
Swim up.
How is the process of the sperm swimming up to the temperature gradient called?
Thermotaxis.
From where are steroids released?
The cumulus-oocyte-complex.
What do the steroids stimulate?
Calcium influx.
Sperm motility.
What happens in the process of chemotaxis?
Sperm swim up the concentration gradient towards the egg.
From where are chemical released?
The tubules.
What do chemicals facilitate?
Sperm swim up the concentration gradient towards the egg.
What are the sperms observed to do?
Swim against a fluid flow.
What mechanism is the swimming of sperm against fluid flow?
Rheotactic = rheumatoid.
Where does the rheotactic mechanism help the sperm?
Swim against the fluid that maybe moved by the cilia of the tubule in the uterus direction.
What is a spermatozoon?
A stripped down.
A refined.
–> machine.
By what is motility driven?
The tail with mitochondria in the midpiece.
What are the mitochondria in the midpiece?
An ATP supply.
Of what does the head consist?
The nucleus and the acrosome.
From where is the acrosome derived?
The golgi apparatus.
What does the acrosome contain?
Enzymes.
Where do the enzymes contained in the acrosome help?
The sperm digest its way through the cumulus-oocyte-complex.
Why is it extremely difficult to replicate or advance many of the observations now about sperm transport in the female reproductive tract?
Due to ethical issues.
How the observations remain today of sperm transport in the female reproductive tract?
Important insights.
How many ejaculated human sperm out of 14,000,000 reach the oviduct?
1.
How many ejaculated human sperm reach the oocyte out of 14,000,000?
Not known.
What does the arrival of genetic engineering mean?
We can make observations in mice.
To what do the observations in mice help us?
Understand the process of spermatogenesis and fertilisation.
Why are there many limitations of making observations in mice?
Because mice produce litters.
We now appreciate that there are many fundamental molecular differences between human and mouse sperm.
What is the association between number and sperm?
The higher the number, the older the sperm.
What is the reason of the green fluorescence?
Due to the production of an acrosome-specific enzyme.
What is the acrosome-specific enzyme?
Genetically altered.
Why is the acrosome-specific enzyme genetically altered?
To have a GFP tag on it.
Why must the acrosome-specific enzyme have a GFP tag on it?
So it can be seen under a fluorescent microscope.
Where is a single sperm bound?
To the zona pellucida.
Where does the single sperm lie?
On its side.
Not bound by the hook.
What does powerful high resolution microscopy permit?
The observation of proteins at super resolution.
What does tubulin form?
The main structure of the tail.
What is not the tubulin?
Naturally concentrated down the middle.
Where is the glucose transporter found?
In the plasma membrane.
How is the glucose transporter distributed in the plasma membrane?
Evenly.
What does the sperm specific calcium channel CatSper have?
A very distinct spatial resolution along the plasma membrane.
How many stripes does the sperm calcium channel CatSper form down the tail?
4.
Why and how the 4 stripes down the tail of the sperm specific calcium channel CatSper occur?
It is unknown.
How do the sperm swim in normal media?
Normal.
How can azoospermia be diagnosed?
By using the software.
Where can sperm swim?
In a viscous medium.
How is the sperm tail movement characterised?
Elegant.
What does the sperm do as it moves forward?
It rotates.
By what is the sperm driven when it is rotating?
The tail.
What is the tail movement?
It is rolling around a central point.
To what does the sperm tail not move?
Site-to-site.
How is the semen composition characterised?
Complex.
What does semenogelin give to the semen?
Its gelatinous form.
o what is the semenogelin inhibitory ?
To sperm function.
How does the enzyme PSA act?
To degrade the semenogelin.
Help liberate the sperm.
To where are the sperm exposed during storage?
Fluids of lower pH.
To where are the sperm exposed during storage?
Fluids of lower pH.
Where does lower pH help?
Suppress motility.
What is bicarbonate?
A buffering component.
Where are the buffering components added to at ejaculation?
Raise the pH.
What is Zn?
An important ion.
Where does Zn have a role?
In DNA compaction.
PSA, SOD, NOS activity.
As what can fructose and glucose act?
Energy substrates.
Where might prostaglandin have effects on?
Sperm.
Female tract.
What does Zn inhibit?
Hyperactivation.
Capacitation.
When do ion concentrations radically change?
When the sperm are ejaculated in the seminal fluid and in the female tract.
Where is K+ significantly reduced and the Na+ and HCO3- concentrations are significantly increased?
In the female tract.
For what is the regulation of intracellular calcium ion concentration critical?
Regulating the sperm function.
By which factors is semen composed?
Sperm. Semenogelin. PSA. pH buffering components. Ions: citrate, Zn, Ca, Na, Cl, K, Mg. Fructose/glucose. Prostaglandins.
What do superoxide and NO control?
cAMP levels.
Changes in protein phosphorylation.
Nitration.
By what is ROS generation controlled?
Ca.
How is the regulation of intracellular calcium levels characterised?
Critical.
What are some important processes that are necessary in order to permit motility?
Elevated pH - sufficient alone to activate, in vitro.
Semenogelin to breakdown.
Generation of ROS.
For what is elevation of pH vital?
Sperm activation.
When does pH elevation occur?
At ejaculation as the sperm are mixed with the seminal fluids.
What does increasing pH stimulate?
Sperm metabolism.
Why does increasing pH stimulate sperm metabolism?
To supply the cell with the energy required for motility.
What do calcium ions directly activate?
The machinery in the tail.
What effect do calcium ions have when they activate the tail machinery?
A hyperpolarising effect.
Where do calcium ions have a hyperpolarising effect?
On membrane potential.
Why do calcium ions have a hyperpolarising effect on membrane potential?
Due to activation of the calcium-sensitive potassium channel.
What do sperm also have?
A channel.
How is the channel of sperm called?
A proton channel.
HV1.
Where does the proton channel of sperm occur?
In the tail.
What does the proton channel of sperm allow?
Hydrogen ions to leave.
Why does the proton channel of sperm allow hydrogen ions to leave?
To help raise the cytoplasmic pH.
How is pH elevated?
Combination of proteins, ionic buffer, bicarbonate > 5-25mM.
What does alkalinisation stimulate?
Sperm metabolism.
What does calcium influx activate directly?
The axoneme.
What does calcium influx hyperpolarise?
The membrane.
What does recombinant Sg inhibit when added to sperm, over time?
Motility.
How where the experiments done?
By using purified seminal vesicle extracts.
What do the graphs of testing show?
A drop in motility.
A speed of swimming over time.
What does Zinc stabilise?
Sg.
How does Zinc stabilise Sg?
Due to its inhibitory action on PSA.
Where is there a delay upon ejaculation?
In liquefaction.
Why is there a delay in liquefaction in ejaculation?
As the zinc ions must diffuse away.
What do the zinc ions allow when they diffuse away?
The PSA to become active.
How is the Sg protein characterised?
Very influential.
Where does Sg protein affect?
On motility.
Capacitation.
What properties does PSA protein have?
Antibacterial.
How are the antibacterial properties characterised?
Beneficial.
For what are the antibacterial properties of Sg protein beneficial?
For the sperm in the vagina.
For cervical regions.
Where does semenogelin (Sg ) protein originate?
In seminal vesicle.
