Fertilization and early embryology: Recurrent failure in polar body formation and premature chromosome condensation in oocytes from a human patient: indicators of asynchrony in nuclear and cytoplasmic maturation

All oocytes from a patient who had undergone four unsuccessful in-vitro fertilization attempts showed neither a polar body nor pronuclei when examined for fertilization. In 19 inseminated oocytes that were spread for karyotypic analysis, one haploid set of metaphase II chromosomes and a remarkable condensed structure were found. Hormonal and morphological criteria implied that the oocytes had been mature at the time of retrieval. Since non-inseminated oocytes contained only one set of metaphase II chromosomes, the condensed structure appeared to represent the sperm chromatin in the state of premature chromosome condensation due to a block in oocyte maturation. Since the first and second polar body, as well as their chromatin, were undetectable in all the patient's oocytes, a rapid maturation to metaphase II before retrieval and prolonged arrest in this state before fertilization, accompanied by degeneration of the first polar body, appear to be responsible for the condition. In accordance with this notion, degenerate spindles (typical of post-ovulatory aged oocytes) and separating chromosomes (probably representing presegregating chromatids) were observed by antitubulin immunofluorescence.