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 unsuccessfulin-vitro fertilization attempts showed neither a polar bodynor pronuclei when examined for fertilization. In 19 inseminatedoocytes that were spread for karyotypic analysis, one haploidset of metaphase II chromosomes and a remarkable condensed structurewere found. Hormonal and morphological criteria implied thatthe oocytes had been mature at the time of retrieval. Sincenon-inseminated oocytes contained only one set of metaphaseII chromosomes, the condensed structure appeared to representthe sperm chromatin in the state of premature chromosome condensationdue to a block in oocyte maturation. Since the first and secondpolar body, as well as their chromatin, were undetectable inall the patient's oocytes, a rapid maturation to metaphase IIbefore retrieval and prolonged arrest in this state before fertilization,accompanied by degeneration of the first polar body, appearto be responsible for the condition. In accordance with thisnotion, degenerate spindles (typical of post-ovulatory agedoocytes) and separating chromosomes (probably representing presegregatingchromatids) were observed by antitubulin immunofluorescence.