Experimental attempts to extend the current preimplantation genetic diagnosis with individual karyotypization of human blastomeres

The drug-induced chromosome condensation using okadaic acid, a potent protein phosphatase inhibitor, was studied in day 1 to day 4 (D1-D4) spare human preimplantation embryos. In order to obtain cells for genetic tests, we developed a modified displacement blastomere biopsy method. During the okadaic acid treatment, approximately 40% of biopsied cells were lost due to heavy changes of the plasma membrane; this detrimental effect of okadaic acid differed markedly with the respect to the age of embryos. In comparison with the natural embryonic mitotic index, day 1 and day 2 embryonic cells gave increased yields of chromosome spreads (up to 51% of the initial D1-D2 cell number); on days 3 and 4 we were not able to obtain from surviving cells more than 31% blastomeres with condensed chromosomes (9% of total D3-D4 cell number). All chromosome spreads were successfully used for recycling in G-banding and subsequent FISH analysis. assisted reproduction / blastomere biopsy / chromosome aberration / fluorescent in situ hybridization (FISH) / G-banding / human early embryo / karyotype / okadaic acid / preimplantation genetic diagnosis Rsum -Effort exprimental orient vers l'largissement du diagnostic gntique de primplantation de la caryotypisation de diffrents blastomres humains. Nous avons tudi la condensation des chromosomes de diffrentes cellules qui taient isoles des embryons humains aberrants de primplantation ages de 1-4 jours (D1-D4), provoque par l'acide okadaic -un inhibiteur fort des phosphatases de protines. Nous avons utilis la mthode modifie de la biopsie d'un blastomre. Cca 40 % de cellules a disparu cause de grandes modifications de la membrane cytoplasmique au cours de l'action de l'acide okadaic. Chez les cellules des embryons de 1 et de 2 jours, nous avons obtenu le nombre lev de chromosomes (jusqu' 51 % du nombre initial de cellules). En ce qui concerne les cellules de 3 et 4 jours, nous n'avons russi obtenir que 31 % de blastomres avec