A phase of chromosome aggregation during meiosis in human oocytes.
A higher rate of chromosomal abnormality occurs in human oocytes compared with other animal oocytes. In this study, chromosome movement has been successfully observed during first and second meiosis using a time-lapse culture system and a differential interference contrast inverted microscope. In human oocytes, a specific sequence of early maturation changes was observed. Following the completion of nucleolar breakdown, chromosomes were assembled into a single aggregation that heralded the start of nuclear membrane breakdown. The chromosome aggregation phase (gere phase) persisted after germinal vesicle (GV) breakdown, lasting several hours, and a similar gere phase (chromosome gathering) occurred after the first polar body extrusion, lasting 1-4 h. In contrast, in mouse GV oocytes, nucleolar and nuclear membranes started to break down almost at the same time. A chromosome aggregation phase was not observed in mouse oocytes. The discovery of a gere phase during human oocyte maturation may provide important information related to the mechanism of abnormal chromosomal segregation, which often occurs during meiosis.
Otsuki
Junko
J
Nagai Clinic, 607-1 Kamihikona, Misato, Saitama 341-0004, Japan. otsuki.midori.junko@gmail.com
Nagai
Yasushi
Y
D000818:Animals; D020090:Chromosome Segregation / Q000502:physiology; D002877:Chromosomes, Human / Q000502:physiology*; D006801:Humans; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D008857:Microscopy, Interference; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic