a1 Department of Animal Sciences, University of Missouri-Columbia, Columbia, Missouri, USA
Porcine oocyte-cumulus complexes were cultured in bovine serum albumin(BSA)-free North Carolina State University (NCSU)23 medium containing porcine follicular fluid (10%), cysteine (0.1 mg/ml)and hormonal supplements (eCG and hCG: 10IU/ml each) for 22h. They were then cultured in the same medium but without hormonal supplements for an additional 22h. After culture, cumulus cells were removed and oocytes were co-incubated with frozen-thawed ejaculated boar spermatozoa in tissue culture medium (TCM)199 containing caffeine (5mM), fetal calf serum (FCS; 10%) and varying concentrations (26–56 mM)of NaHCO3 for 9h(experiment 1). In experiment 2, chlortetracycline (CTC) was used to assess the functional state of spermatozoa incubated under different NaHCO3 concentrations. Experiment 3 examined the effect of FCS (1% and 10%)and NaHCO3 (26 and 46 mM) on fertilisation parameters. Compared with 26 mM, penetration rate was significantly higher (p<0.05)at 36–56mM NaHCO3. Polyspermy showed a similar pattern although no difference was observed between 26 and 36 mM. At 46mM NaHCO3, the mean number of spermatozoa (MNS) penetrated per oocyte increased significantly (p< 0.05). A significantly higher proportion of spermatozoa were capacitated and acrosome reacted at 46 and 56mM NaHCO3, respectively. The fertilisation medium containing 46mM NaHCO3 and 1% FCS showed a higher penetration rate (84%)with a relatively low incidence of polyspermy (39%). The results indicate that NaHCO3 stimulates capacitation and/or the acrosome reaction of boar spermatozoa in a dose-dependent manner and thus affects fertilisation parameters.
(Received December 17 1996)
(Accepted February 19 1997)
c1 Billy N. Day, University of Missouri-Columbia, Department of Animal Sciences, 159 Animal Sciences Research Center, Columbia, MO 65211, USA. Tel: +1(573)-882-7555. Fax: +1(573)-884-7827.
p1 Present address: Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700, Japan.
1 Department of Animal Sciences, University of Missouri-Columbia, Columbia, Missouri, USA.
3 Department of Animal Sciences, Kon-kuk University, Seoul 133-701. Korea.