Processing sperm for different assisted reproductive techniques:
In most cases, semen collection is performed by way of masturbation in a sterile container.
However, there are indications (natural, medical, etc.), that require extraction of sperm by inserting a needle under local anesthesia directly into the testis/es (TESE method).
TESE is a procedure that applies when seminal vesicles are blocked; it happens after vasectomy or after severe trauma or infection, or when the patient is born without vesicles (congenital absence of vas deferens).
Sometimes, in case of retrograde ejaculation, sperm cells can be collected from the bladder (urine).
Rarely, in men with injuries affecting the spinal cord, ejaculation is facilitated by electrical stimulation (electroejaculation).
Sperm cells must undergo biochemical and structural changes, known as capacitation before an egg is fertilized.
Capacitation (which normally occurs in woman’s reproductive tract) should be performed in embryology laboratory immediately prior to insemination. Motile sperm cells are processed and activated in specific environments.
By applying various techniques, the performance of sperm cells with low motility may improve.
1. Density gradient centrifugation:
Density gradient centrifugation is a method for separating sperms cells, aiming at selection of the most motile sperm population and reducing non-motile sperm cells, cell detritus, cells from the spermatogenesis and from the immune system (leukocytes, lymphocytes, erythrocytes).
2. Swim up:
In this method, separation is based on sperm cells’ motility.
After centrifugation, the precipitated sperm cells are layered with medium and placed at a certain angle in order to allow the sediment to have a larger surface for contact with the medium. The spermatozoa swim towards the surface of the medium and the most motile are placed the closest to the surface.
3. Swim up after Density gradient centrifugation:
It combines the two main methods of separation in order to obtain “the best” possible sperm cells.
4. Magnetic-activated cell sorting (MACS):
Based on the use of annexin V-coated microbeads. It is used to differentiate expressed phosphatidylserine (apoptotic) sperm cells from those with an intact plasma membrane.
5. Combining all methods of sperm cells selection.
It allows extraction of the best sperm cells by using each methodology.