view - Department of Reproduction, Obstetrics and Herd Health
view - Department of Reproduction, Obstetrics and Herd Health
view - Department of Reproduction, Obstetrics and Herd Health
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CHAPTER 1.2<br />
Recently, a new technique for concentrating equine semen was described. Based on a filter<br />
with a hydrophylic synthetic membrane that does not allow sperm passage. Following filtration, up<br />
to 95% <strong>of</strong> sperm cells could be recovered without affecting sperm motility <strong>and</strong> viability (Alvarenga et<br />
al., 2010).<br />
Selection <strong>of</strong> spermatozoa<br />
Different techniques are available for separation <strong>and</strong> selection <strong>of</strong> spermatozoa. Separation is<br />
the most straightforward procedure, in which the only objective is to separate the spermatozoa from<br />
the seminal plasma. This is done by centrifugation <strong>and</strong> can be achieved as described above (Henkel<br />
<strong>and</strong> Schill, 2003). In contrast, selection aims at simultaneously separating the spermatozoa from the<br />
seminal plasma <strong>and</strong> selecting a sperm subpopulation based on sperm quality characteristics.<br />
Migration, filtration <strong>and</strong> colloid centrifugation are three techniques available for sperm selection<br />
(Morrell <strong>and</strong> Rodriguez-Martinez, 2009).<br />
→ Migration<br />
Sperm selection by migration relies on the ability <strong>of</strong> motile spermatozoa to move from one<br />
suspension into a medium <strong>of</strong> a different composition. The original sperm population (diluted semen<br />
or a washed sperm pellet) can be either underneath, on top <strong>of</strong> or beside the migration medium.<br />
During an incubation stage the spermatozoa migrate actively into the selection medium (Morrell <strong>and</strong><br />
Rodriguez-Martinez, 2009) indicating this technique selects spermatozoa based on motility rather<br />
than on morphology, chromatin integrity, viability <strong>and</strong> acrosome integrity (Somfai et al., 2002). The<br />
major disadvantage <strong>of</strong> migration is the low recovery rate, rendering it impractical for clinical use for<br />
preparing AI doses (Morrell <strong>and</strong> Rodriguez-Martinez, 2009).<br />
→ Filtration<br />
Filtration is achieved by the interaction <strong>of</strong> spermatozoa with the different filter substances.<br />
Non-viable spermatozoa adhere more to the filter substrate compared to motile spermatozoa, as<br />
such increasing the quality <strong>of</strong> the sample following filtration (Bussallou et al., 2008). Filtration allows<br />
for processing <strong>of</strong> relative large volumes, but leukocytes <strong>and</strong> debris also pass by the filtration process.<br />
Additionally, the sperm remains suspended in the same volume containing the seminal plasma, as<br />
such requiring an additional centrifugation step (Henkel <strong>and</strong> Schill, 2003), or possibly a filtration to<br />
increase the concentration (Alvarenga et al., 2010).<br />
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