PRESENCE OF ORGANIC OSMOLYTES IN MATURATION MEDIUM ENHANCES CYTOPLASMIC MATURATION OF PORCINE OOCYTES

The effects of organic osmolytes on cytoplasmic maturation of porcine oocytes were examined in maturation medium (modified Whitten's medium) containing various NaCl concentrations. The presence of organic osmol ytes, such as taurine and sorbitol, at 6 and 12 mM in maturation mediu m containing 68.49 or 92.40 mM NaCl increased oocyte glutathione conte nt. Microfilament organization in oocytes was disrupted in maturation medium containing the higher level of NaCl (92.40 mM). However, supple mentation with 12 mM sorbitol to the medium reduced the severity of th e abnormality. Early embryonic development in vitro to the blastocyst stage was 8.3 +/- 0.9% for oocytes matured in modified Whitten's mediu m (68.49 mM NaCl) supplemented with 12 mM sorbitol, and 7.9 +/- 0.8% i n modified NCSU23 medium (containing 108.73 mM NaCl, 7 mM taurine, 5 m M hypotaurine, and 1 mM glutamine), compared to 4.7 +/- 0.6% in modifi ed Whitten's medium (68.49 mM NaCl), which did not contain organic osm olytes. These results indicate that the presence of organic osmolytes, such as sorbitol and taurine, reduces the detrimental effects of high NaCl concentration in media used for the maturation of porcine oocyte s. This effect is reflected by oocyte glutathione content and microfil ament organization at the end of maturation and early development foll owing in vitro maturation and in vitro fertilization.