Cytological studies of human zygotes exhibiting developmental arrest.
Developmental arrest of 111 (approximately 5%) fertilized ova which had formed two pronuclei was observed during a 5-year period of an in-vitro fertilization programme. At least 30 zygotes demonstrated visible pronuclei at 44-66 h after insemination, and 42 zygotes fragmented. Of the 107 prepared zygotes, 97 were informative and revealed that developmental arrest occurred at different stages of the cell cycle: from interphase (n = 48), to transition interphase-prophase (n = 20), to prophase (n = 11), and to metaphase (n = 13). The latter 13 zygotes were characterized by chromosome sets as follows: haploid (n = 2), diploid (n = 6), triploid (n = 1) and tetraploid (n = 4). Another five zygotes demonstrated different numbers of metaphase chromosomes (between 10 and 40), as well as prematurely condensed chromosomes (PCC) as a result of marked asynchrony in pronuclear morphogenesis. A total of 18 zygotes exhibited asynchrony in the morphology of the two pronuclei. It is concluded that abnormal chromosome sets and pronuclear asynchrony might be causes for early developmental arrest.
Schmiady
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Freie Universität Berlin, Universitätsklinikum Rudolf-Virchow, Frauenklinik Charlottenburg, Germany.
Kentenich
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D000328:Adult; D002453:Cell Cycle; D002467:Cell Nucleus / Q000648:ultrastructure; D002877:Chromosomes, Human / Q000648:ultrastructure; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007399:Interphase; D008297:Male; D008677:Metaphase; D008938:Mitosis; D011003:Ploidies; D015053:Zygote / Q000254:growth & development* / Q000648:ultrastructure