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Title: IN VITRO PRODUCTION OF PIG EMBRYOS: CULTURE MEDIA AND BOAR COMPARISONS

Author
item Long, Charles
item Dobrinsky, John
item Johnson, Lawrence

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Laboratory objectives of producing gender selected offspring and improving viability of cryopreserved embryos requires improved in vitro techniques. In vitro production systems are currently hindered by polyspermic penetration of oocytes, low developmental rates, and decreased cell numbers of resulting embryos. It was our objective to establish a reliable in vitro oembryo production system for testing sperm sorting procedures and to provide large numbers of embryos for use in further experiments. These experiments set up a fully functional system for production of embryos in vitro. Sperm from multiple sires can be utilized to successfully penetrate oocytes and resulting zygotes subsequently cultured to peri-implantation stages. Improving the culture media increased the development rates and viability of embryos, as measured by increased cell numbers. Procedural modifications reduced the time and technical effort necessary for completion of in vitro maturation and fertilization of oocytes. These results allow us to test modifications to the Beltsville Sperm Sexing Technology in an in vitro bioassay for sperm performance. Additionally, large numbers of embryos can be produced to be used further in cryopreservation and embryonic development studies.

Technical Abstract: The utilization of in vitro produced pig embryos for research is dependent upon the development of improved methodology. Our objective was to establish a consistent in vitro embryo production (IVP) system and subsequently utilize the procedures to evaluate system components. To summarize the IVP system, 403 inseminated oocytes from a total of 2243 were eanalyzed across 17 replicates for maturation and fertilization efficiency, while 1838 zygotes were cultured in 26 replicates for developmental data. Monospermic penetration averaged 31.8%+7.3 (SEM) while polyspermy was 30.8%+17.2. Cleavage rate was 44.9%+16.1 with 21.8%+7.5. of fertilized oocytes and 51.9%+15.9 of cleaved embryos developing to blastocysts. For culture medium comparison, fertilized oocytes cultured in either BECM-6, BECM-7, NCSU-23 or NCSU-23aa resulted in 4.0, 4.9, 19.8 and 13.6% (+ 3.2 SEM) blastocysts by d7 with an average cell number of 44.4+ 9.0, 65.1+8.2, 61.3+4.5 and 64.4+4.8 cells, respectively. The IVP procedures consistently produced zygotes from several different boars, capable of forming blastocysts in vitro. Comparison of developmental rates among several boars indicated that this system is variable among boars, but not strictly boar dependant. Culture media comparisons suggest that NCSU-23 yielded a higher percentage of blastocysts in this IVP system.