Abstract
Males homozygous for chromosomal translocations were mated to karyologically normal females. The resulting embryos, after incubation for 16-18 h, were prepared for cytogenetic analysis. Of the 62 embryos analysed, 54 (7.8%) were heteroploid or contained a major heteroploid cell line. Each of the 638 normal 2n embryos contained one marker and one normal chromosome, indicating that none arose from gynogenesis. Thirteen homogeneous haploid embryos were identified; 24 embryos were chimaeric 1n/2n and one was 1n/3n. All haploid cell lines contained a marker chromosome indicating androgenetic origins. The 9 homogeneous triploid (3n) embryos and the 3n cell line in a single 1n/3n embryo contained a single marker. All resulted from fertilization by single spermatozoon of eggs that were diploid as a result of suppression of the second meiotic division. The 3n lines of two 2n/3n embryos were derived from other mechanisms. A single homogeneous tetraploid (4n) embryo and the 4n cell lines of three 2n/4n mosaic embryos each contained two marker chromosomes and presumable resulted from failure of cytokinesis in an early cleavage division.
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