Spermatogenesis Flashcards
What is Spermatogenesis?
The production of sperm in the testis.
What do the same hormones that regulate the female cycle drive?
Spermatogenesis.
What are the levels of hormones that drive the female cycle and spermatogenesis?
Different.
What does FSH stimulate?
The production of androgen binding protein (ABP) by Sertoli cells.
The formation of the blood-testis barrier.
Where does FSH help?
Concentrate testosterone in the testis.
Maintain the correct structures that are necessary for coordinated spermatogenesis.
Where does negative feedback occur in spermatogenesis?
At the level of the brain.
Why does negative feedback occur at the level of brain in spermatogenesis?
To regulate testosterone production.
Where does negative feedback at brain level in spermatogenesis occur?
Through the actions of testosterone and inhibin.
What does testosterone do in the negative feedback at brain level in spermatogenesis?
Inhibits GnRH + LH release.
What does inhibin do in the negative feedback of spermatogenesis at brain level?
Inhibits FSH release.
Of what is the male reproductive system composed?
Testis.
Accessory organs.
Connecting ducts.
What does the seminal vesicle produce?
Seminal fluid.
What does seminal fluid add?
Components =like fructose, citric acid and prostaglandins.
Why does seminal vesicle produce seminal fluid?
To ejaculate.
What are some of the components of seminal fluid, like fructose?
Useful to the sperm.
Why are the components of seminal fluid useful to the sperm?
For energy.
What do prostaglandins influence?
Sperm and female tract.
What do the secretions of the prostate include?
Proteolytic enzymes.
Prostatic acid phosphatase.
Fibrinolysin.
What do prostate secretions help?
Liquefy semen.
What are zinc and prostate-specific antigen?
Essential components.
What is the role of PSA?
Liquifying the gelatinous semen.
How does PSA liquify the gelatinous semen?
By breaking down a protein matrix.
How is protein matrix, that breaks down so PSA can liquify the gelatinous semen, called?
Semenogelin.
What does Semenogelin coat?
The sperm.
Why does the vas deference contract?
To help expel the sperm.
How does the vas deferens appear in the process of vasectomy?
Cut.
Tied.
Where is the longitudinal section of a testicle?
In the top LHS.
How are the seminiferous tubules shown in the longitudinal section of a testicle?
Tightly packed.
What are the seminiferous tubules?
The site of spermatogenesis.
Where do the sperm germ cells sit in the tubule TS?
Against the basement membrane.
By what are the sperm germ cells divide in the tubule TS?
Mitosis.
Why are the sperm germ cells divide by mitosis?
To produce one daughter cell.
Replace the divided cell and one cell that will undergo meiosis.
What will the cell that will undergo meiosis become?
4 Sperm cells.
Where does spermatogenesis occur?
Outward towards the lumen.
Why does spermatogenesis occur outward towards the lumen?
So the sperm can be taken to the site of storage in the epididymis.
With what is a tissue section stained?
A dye that binds to the DNA in the nucleus.
Of what is the tubule packed?
Cells.
What are the positions of the Leydig and Sertoli cells?
Important.
Where are the Leydig cells found?
Around between tubules.
Where can Leydig cells and testosterone diffuse?
Across the basement membrane.
Where are the Sertoli cells found?
Inside.
What do the Sertoli cells form?
The blood-testis barrier.
What does the blood-testis barrier protect?
The developing sperm.
Where are the blood vessels found?
Outside the tubule.
Where are the cellular connections found?
Between adjacent Sertoli cells from the blood-testes-barrier.
Where are the germ cells/spermatogonia?
Beneath BTB on the basement membrane.
Through where must a daughter cell pass?
The barrier.
How does the daughter cell pass through the barrier?
In a controlled, regulated manner as the barrier must loosen.
Where do the cell moves as meiosis proceeds?
Towards the lumen.
What does one cell become as meiosis proceeds?
4.
How do the 4 cells produced by one cell in meiosis remain?
Connected.
By which factors do the 4 cells produced by one cell in meiosis remain connected?
Cytoplasmic bridges.
Until when do the spermatids remain connected in meiosis?
Morphological changes give the cells its characteristic appearance.
What is the characteristic appearance of a spermatid?
A long tail and elongated head.
What happens to the excess cytoplasm and cellular components?
They get lost.
Where do excess cytoplasm and cellular components lost?
In residual bodies.
What can Sertoli cells do?
Phagocytose.
Destroy damaged sperm cells.
How many sperms are produced per heart beat?
1000.
How many days does a single wave of spermatogenesis take over in a man?
70 days.
When do morphological and DNA changes occur?
During spermatogenesis.
From where are spermatogonia that reside near the basement membrane derived?
Spermatogonia stem cells (SSC).
Where do spermatogonia near the basement membrane, derived from spermatogonia stem cells enter?
Spermatogenesis.
Into what types do spermatogonia near basement membrane, derived from spermatogonia stem cells, differentiate?
As cells.
By what are spermatogonia that are differentiated into type As cells followed?
A1-A4.
Intermediate (In) spermatogonia.
To what do type B spermatogonia transform?
Preleptotene spermatocytes.
What are the preleptotene spermatocytes?
The germ cells that must be transported across the blood-testis barrier (BTB).
What does BTB divide?
The seminiferous epithelium.
Into what do BTB divide the seminiferous epithelium?
The ad luminal and the basal compartment.
What does ad luminal mean?
Towards the lumen.
As what are Meiosis 1 and 2 and all the cellular events of post meiotic development known?
Spermiogenesis.
Spermiation.
What is spermiation?
The process by which mature spermatids are released from Sertoli cells into the seminiferous tubule lumen prior to their passage to the epididymis.
Where do Meiosis 1 and 2 and all the cellular events of post meiotic development take place?
In the ad luminal compartment.
What happens during Meiosis 1 and 2 and all the cellular events of post meiotic development?
Millions of spermatozoa are formed efficiently.
Developing germ cells are being transported progressively.
From where are developing germ cells transported?
The basal.
To where are developing germ cells transported?
The ad luminal compartment.
The edge of the seminiferous tubule lumen.
Where are mature spermatozoa released at?
Spermiation.
Where do mature spermatozoa enter?
Seminiferous tubule lumen.
Why do mature spermatozoa enter the seminiferous tubule lumen?
For their eventual maturation.
Where do mature spermatozoa eventually maturate?
In the epididymis.
When do DNA changes occur?
During meiosis of 2 chromosomes.
At what stage does the pairing of homologous chromosomes happen?
The zygotene stage.
What happens to the DNA by the pachytene stage?
It is duplicated.
When does crossing over occur?
At the diplotene stage.
What factors are formed when Meiosis 1 proceeds?
2 secondary spermatocytes.
Through what do the 2 secondary spermatocytes transited?
Meiosis 2.
What do the 2 secondary spermatocytes form when they are transited through meiosis 2?
4 interconnected spermatids.
What do the 4 interconnected spermatids undergo?
Morphological changes.
During what did the 4 interconnected spermatids undergo morphological changes?
Spermiogenesis.
By what is spermiogenesis followed?
Spermiation.
What do most sperms have?
A tail.
What can the morphology of the head do?
Differ.
Where does the change of the head morphology differentiation is most notable seen?
In mouse sperm.
Why is the function of the hook not known?
Because, the sperm doesn’t bind to the egg using the hook.
How does the human sperm look?
A spatula with a flat oval head.
With what does the size of the sperm heads appears to be correlated?
Genome size.
What are the thickness of flagella in mammalian sperm?
Larger.
What does the larger thickness of flagella in mammalian sperm reflect?
The more challenging swimming environment in vivo animals compared to the external fertilisers.
By what is spermatogenesis driven?
The same hormones as oogenesis.
What are the three key cell types that are necessary for spermatogenesis?
- Spermatogonia sperm cells.
- Leydig cells.
- Sertoli cells.
What stage event is spermatogenesis characterised?
A complex multi stage event.
What does spermatogenesis involve?
Molecular Genomic Physiological Morphological --> changes.
How is the sperm cell shape across species characterised?
Highly conserved.
