Effects of caffeine,Ca++, capacitation time,and strain on in vitro fertilization in mice |
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Authors: | J. W. Dodds G. E. Seidel |
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Abstract: | Oocytes (N=2922) were collected from superovulated female C57B16/J X DBA2/J (B6D2F1) mice and distributed among 48 treatments consisting of a 2×3×2×2×2 factorial design. The factors were strain of spermatozoa, B6D2F1 or SJL/J; caffeine concentration in the fertilization medium, 0,2, or 6 mM; time oocytes were exposed to sperm, 1 or 2 hours; Ca++ concentration in the capacitation medium, 0 or 1.8 mM; and capacitation time, 1 or 2 hr. Ova were observed 400 min after they were initially exposed to 105 spermatozoa per ml. Ova with two or more pronuclei and a second polar body were considered fertilized, In vitro embryonic development was monitored for 5 days. B6D2F1 spermatozoa resulted in consistently higher rates of fertilization than SJL spermatozoa, 77.5% vs 38.7% when averaged over other treatments. Caffeine concentrations of 0,2, and 6 mM resulted in respective mean fertilization rates of 50.1%, 58.8%, and 65.4% (P<0.005) when averaged over other factors. Fertilization rates of ova exposed 1 and 2 hr to sperm were 53.0% and 63.3% (P<0.005). B6D2F1 spermatozoa capacitated in medium with 1.8 mM Ca++ fertilized more ova (P<0.01), 83.1%, than when no Ca++ was present, 71.9%; this effect was absent with SJL spermatozoa. The effect of capacitation time depended on strain. Fertilization rates with B6D2F1 spermatozoa were higher, 80.1%, with a 2-hour capacitation time than with a 1-hour capacitation time, 75.0%. Exactly the opposite was true for the SJL spermatozoa; 43.4% for the 1-hour and 34.1% for 2-hour capacitation (P<.01). Development to the blastocyst stage was significantly greater (P<0.025) for ova fertilized by B6D2F1 (26.8%) than by SJL spermatozoa (17.7%). |
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Keywords: | in vitro fertilization caffeine mice capacitation polyspermy |
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