Early bovine embryos (two - to sixteen blastomeres) produced in vitro were cytogenetically analysed to determine the incidence of haploidy. Follicular oocytes were matured in vitro and inseminated with sperm prepared using the swim up method. After 2-3 days of culture, chromosome slides were prepared according to the air-drying technique and stained with Giemsa. Altogether 202 embryos produced metaphase spreads. Of these 4.5% were pure haploid embryos and 5.5% displayed a haploid cell line within mosaic embryos (n/2n and n/3n). The occurrence of haploid embryos observed in this study was compared to results of other studies and a possible origin of haploidy was discussed.
Hybridisation is one of the most important methods of successful breeding of bakers yeast Selection of diploid strains, isolation and selection of haploids plays crucial role in process. In this article individual stages of isolation and selection of biotin-independent haploids were described. Sporulation yield and spores survivability were estimated. Haploid strains isolated during experiments enable further researches into obtaining new, prototrophic to biotin, strains of Saccharomyces cerevisiae.