PHYSIOLOGIST OF SPERMATOZOA AT HIGH DILUTION RATES: THE INFLUENCE OF SEMINAL PLASMA

Authors: MAXWELL, W.M.C. - UNIVERSITY OF SYDNEY; Johnson, Lawrence

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Application of sexed sperm technology to the industry is dependent on many refinements of methods that are critical to maintaining the physiological integrity of the sperm cell. High dilution is one of the factors associated with sperm sorting by flow cytometry. Sperm are most viable in concentrated solutions, both in vivo and in vitro. It was found that seminal plasma is useful when added to the sorted sperm. It is in essence a replacement for the seminal plasma benefits that are lost when sperm are flow sorted. Functional capacitation that happens prematurely in sorted sperm can be reversed with the addition of seminal plasma to the sorted sperm suspension. Application of these principles to maintaining viability in sorted boar sperm should be useful to enhancing the wider use of sorted sperm in the pig.

Technical Abstract: Extensive dilution of spermatozoa, as occurs during flow-cytometric sperm sorting, can reduce their motility and viability. These effects may be minimized by the use of appropriate dilution and collection media, containing balanced salts, energy sources, egg yolk and some protein. Dilution and flow-cytometric sorting of spermatozoa, which involves the removal of seminal plasma, also destabilizes sperm membranes leading to functional capacitation. This membrane destabilization renders the spermatozoa immediately capable of fertilization in vitro, or in vivo after deposition close to the site of fertilization, but shortens their lifespan, resulting in premature death if the cells are deposited in the female tract distant from the site of fertilization or are held in vitro at standard storage temperatures. This functional capacitation can be reversed in boar spermatozoa by inclusion of seminal plasma in the medium used to collect the cells from the cell sorter and, consequently, reduces their in vitro fertility. It has yet to be determined whether seminal plasma would have similar effects on flow cytometrically sorted spermatozoa of other species, and what its effects might be on the in vivo fertility of flow sorted boar spermatozoa.