RESUMO
Chromosomal mosaicism has been reported in in vitro-cultured embryos at early cleavage stages, as well as in morulae and blastocysts. We have assessed the incidence and pattern of mosaicism during in vitro development of human embryos from early-cleavage stages to morula and blastocyst. Fifty spare embryos were fixed for fluorescence in situ hybridization (FISH) analysis for chromosomes X, Y, 13, 18, and 21 on days 2 or 3 (4- to 10-cell stage) (n = 16), on day 4 (morula stage) (n = 14), on day 5 (pre-expanded blastocyst) (n = 5), and the expanded blastocyst stages (n = 15). Blocked embryos (no cleavage observed within the last 24 hr) were not included. A total of 2367 cells were analyzed. Four early-cleavage stage embryos were found uniformly diploid; all of the others were mosaic for the chromosomes analyzed (mean diploid nuclei 48.3% +/- 28.7). All of the embryos at more advanced developmental stages, except one fully normal morula, had mosaic chromosome constitutions, with an increase in the percentage of diploid cells in morulae, pre-expanded, and expanded blastocysts, respectively (mean diploid nuclei 78.6% +/- 11.7, 66.0% +/- 20.8, 79.6% +/- 12.8), in comparison with earlier stages. Hypotheses about the origin of mosaicism and embryo regulation mechanisms will be discussed.
Assuntos
Desenvolvimento Embrionário e Fetal/genética , Mosaicismo , Aneuploidia , Blastocisto/ultraestrutura , Cromossomos Humanos/genética , Fase de Clivagem do Zigoto/ultraestrutura , Diploide , Feminino , Fertilização in vitro , Humanos , Hibridização in Situ Fluorescente , Técnicas In Vitro , Masculino , Modelos Genéticos , Mórula/ultraestruturaRESUMO
Here we report the association of giant platelets and an increase in platelet volume in a 19-month-old black female with de novo del 11q24-qter. The deletion, which was visible on karyotype, was further confirmed and more precisely localized by fluorescence in situ hybridization studies (FISH) that showed the deletion to lie distal to the MLL gene region (11q23). Clinically, the case presented less severe symptoms than Jacobsen syndrome-the well known partial deletion of the distal end of chromosome 11. Platelet glycoproteins CD 41, CD 42a, C 42b, CD 61, and PAC-1 were also assayed and found to be normally expressed. To our knowledge, giant platelets are described for the first time in the relevant deleted region.
