MEIOSIS-I IN HUMAN OOCYTES

Oocytes aspirated from women undergoing laparoscopic sterilisation wer e matured in vitro from the germinal vesicle stage. They showed that g erminal vesicle breakdown spanned a period of about 12 h; the oocytes were at diakinesis by 12 h, and at metaphase I by 16 h where they rema ined for a further 10-12 h. Anaphase I took place after about 26 h. Th e meiotic preparations lacked the clarity of chromosome definition see n in mouse oocytes and accurate chiasma counts could not be made. Howe ver univalents at first meiotic metaphase could be detected without am biguity and were found in women significantly older than those whose m etaphase I oocytes contained bivalents only.