Experimentally produced diploid〈‐〉triploid mouse chimaeras develop up to adulthood

Abstract

Spontaneous diploid-triploid chimaeras occur sporadically in various mammalian species including man, but so far have never been produced experimentally. In order to get a deeper insight into the developmental consequences of this anomaly, we have developed two procedures that enabled for the first time to produce routinely diploid-triploid embryos, foetuses, and animals in the mouse. These procedures are: (1) aggregation of cleaving diploid embryos with triploid embryos produced by suppression of the second polar body in zygotes, and (2) fusion of a haploid karyoplast with one blastomere of the two-cell diploid embryos. The first procedure yielded 23 living and 6 dead postimplantation embryos and foetuses (age: 8th-19th day) out of which 22 were chimaeric. In addition, three chimaeric neonates reached adulthood. Two animals were fertile, and one--an overt chimaera--was an infertile male. The rate of postimplantation development of aggregation chimaeras was normal or only slightly retarded, and with one exception the foetuses were morphologically normal. Generally, the highest contribution of the 3n component in extra-embryonic structures was noted in the yolk sac, and usually it was higher than its contribution to the organs of the body. Chimaerism was most often noted in the liver, the heart, the intestine, and the lungs. Participation of triploid cells to all tissues studied, both in the body and in extra-embryonic structures, appeared to decrease slightly as development progressed. The second procedure yielded 10 foetuses and 6 adults. Three foetuses were chimaeric. Six fertile adults were probably non-chimaeras: the triploid component was absent in the coat and in the blood.

Identical triplets and twins developed from isolated blastomeres of 8- and 16-cell mouse embryos supported with tetraploid blastomeres

“…Moreover, in 6 out of 10 examined cases, the tetraploid cells predominated in the yolk sac. Because we observed the same phenomenon in diploid↔triploid mouse chimaeras (Suwinska et al, 2005), this may reflect the general tendency of polyploid cells to colonise preferably the yolk sac and/or survive better in this extra-embryonic structure.…”

Experimental embryonic-somatic chimaerism in the sheep confirmed by random amplified polymorphic DNA assay

“…West and Flockhart, 1994;Wang et al, 1997;Tarkowski et al, 2001;Suwinska et al, 2005). Unfortunately, isozymes of glucose-6-phosphate isomerase could not be used as the marker of chimaerism in the sheep, since two (Beatty, 1983) or three (Rasero et al, 1993) isozymes are found in each breed and there are only quantitative differences in their expression between the breeds.…”

Foetal fibroblasts introduced to cleaving mouse embryos contribute to full-term development

“…The absence of hybrid GPI-1AB isozyme from days 7 to 8 egg cylinders found in this study may be due to delayed expression (like that described above) or to insufficient number of hybrid cells, falling below 1% of the studied sample, which precludes detection in GPI electrophoretic identification (Chapman et al 1972). GPI isozymes were early (Chapman et al 1972, Gearhart & Mintz 1972a,1972b and continuously (West & Flockhart 1994, Wang et al 1997, Suwinska et al 2005 used as markers of chimerism in the mouse. In day 9, embryonic chimeras that developed after aggregation of eight-cell embryos varying in GPI isozymes, no heterodimeric form was found thus excluding cell fusion until this stage (Gearhart & Mintz 1972a).…”

“…Cells of XY constitution in the gonad determine its differentiation into testis (for review, see McLaren (1984)). Triploid cells in chimeras express coat colour markers (Suwinska et al 2005). Perhaps, hybrid tetraploid cells derived from FFs do not enter the skin or they do not produce pigment there.…”