AN IMPROVED METHOD FOR CHROMOSOME PREPARATIONS FROM BOVINE OOCYTES AND ZYGOTES OBTAINED BY IN VITRO MATURATION AND FERTILIZATION TECHNIQUES UN MÉTODO OPTIMIZADO PARA EL ANÁLISIS CROMOSÓMICO DE OVOCITOS Y CIGOTOS OBTENIDOS MEDIANTE TÉCNICAS DE MADURACIÓN Y FECUNDACIÓN IN VITRO

Matured bovine oocytes and zygotes obtained by in vitro maturation and fertilization techniques (IVM and IVF) were cytogenetically prepared by using an improved method for chromosome preparations. The method, which involves use of trypsinizedhypotonic solution plus a vortex-agitated system and very cold two-step fixation process, contributes to weaken the zona pellucida and allows the swelling of oocytes and zygotes which helps the subsequent spreading of the chromosomes. This method permits to obtain preparations of good quality for examining the number and