EFFECT OF DIFFERENT PREMATURATION TREATMENTS ON IN VITRO MATURATION OF EQUINE OOCYTES AND SUBSEQUENT COMPETENCE FOR NUCLEAR TRANSFER

M. SANSINENA, B. REGGIO, D. HYLAN, A. KLUMPP, D. PACCAMONTI, S.K. LYLE, R.S. DENNISTON AND R.A. GODKE

Havemeyer Foundation Monograph Series

R & W (Newmarket) Limited

Lugar: Suffolk, UK; Año: 2004 vol. 12 p. 23 - 25

1472-3158

The low efficiency of the somatic cell nuclear transfer (NT) procedure requires that large numbers of meiotically competent equine oocytes must be available for maturation. In vitro maturation rates of equine oocytes are generally lower and more variable than those of other domestic species. In a recent study investigating oocyte meiotic competence as related to granulosa cell apoptosis, Dell´Aquila et al. (2003) reported that although follicle size was not significantly correlated to apoptosis, the proportion of oocytes maturing in vitro was significantly higher in oocytes issuing from apoptotic follicles than in those issuing from healthy follicles. Also, it was found that significantly more expanded than compact oocytes originated from apoptotic follicles. This supports previous studies that reported the compact oocytes having a lower meiotic competence (Alm and Hinrichs 1996; Hinrichs and Williams 1997) and slower maturation rate (Zhang et al. 1989; Hinrichs et al. 1993; Alm and Hinrichs 1996). The first experiment was conducted to evaluate the nuclear status of equine oocytes matured in vitro using a sequential maturation medium. A second study was conducted to evaluate the effect of roscovitine pre-maturation in oocytes from small equine ovarian follicles and to use these in vitro matured oocytes for equine NT procedures.