Sperm processing procedures that mimic the sperm separation abilities of periovulatory mucus can favorably influence reproductive outcome. These methods analogously and effectively filter progressively motile and morphologically normal sperm from the overall sample population. The resultant sample contains an enriched sperm population with higher fertilizing potential.
Central to this process, as detailed in the previous section, is the separation and elimination of decapacitation factor(s) and contaminants from the seminal plasma. These may be in the form of cellular debris (gelatinous pieces, epithelial cells), bacteria, mycoplasmas, Chlamydia, Trichomonas, and various blood components (leukocytes and erythrocytes).
The goal should be a thorough filtering of motile sperm, and the recovery of most, if not all, viable spermatozoa. Such separation procedures should be reliable, repeatable, and relatively simple to perform.
These separation procedures can be broadly categorized into three major groups:
On occasion, fresh ejaculate is unavailable, making the use of cryopreserved sperm necessary (see Semen cryopreservation procedure, page 119). Prior to use, frozen sperm must be thawed, washed, and processed.
In addition, the deleterious effects of cryopreservation are more pronounced during the thawing and washing procedure, necessitating certain considerations:
Sperm migration method
Procedures based on this concept mimic sperm migration through the pericervical mucus.
Naturally motile sperm will effortlessly and efficiently move from one medium to another, whereas nonmotile or morphologically compromised sperm will have greater difficulty. The sperm migration method inspires procedures which take advantage of healthy sperm's natural tendency for migration.