[Genetic view of the development of the human embryo--the importance of chromosome abnormalities].

Normal embryonic and fetal development requires a diploid chromosome set consisting of a haploid maternal and a haploid paternal chromosome set. Chromosome abnormalities in the zygote are not a rare event, however. Moreover postzygotically different types of aberrations can occur, with different effects on embryonic development. As a consequence embryonic development can be arrested at a very early stage. Other consequences are the impairment of the implantation rate, early spontaneous abortions and developmental abnormalities in newborn children. The results of the analysis of the chromosomal constitution of early embryos show the impact of specific chromosome abnormalities on embryonic development. Normal development on the basis of a normal chromosome set seems to be only one of several possible developments after fertilization.