The Chromosomal Constitution of Embryos Arising from Monopronuclear Oocytes in Programmes of Assisted Reproduction

Table 3

The origin of diploidy in monopronuclear oocytes and ensuing developmental stages.

Material	Origin	Method	Diploid cells	Heteroparental cells	Reference
Karyoplasts	IVF	Y-detection by FISH	6	4 (66.7%)	Levron et al. [11]
Zygotes	IVF	Histone methylation patterns^a	39	39 (100%)	van der Heijden et al. [12]
Embryos	IVF	Cytogenetics/karyotyping	5	2 (40.0%)	Jamieson et al. [20]
Embryos	IVF	Y-detection by FISH	15	9 (60.0%)	Sultan et al. [3]
Embryos	IVF	Y-detection by FISH	56	25 (44.6%)	Staessen and van Steirteghem [7]
Embryos	IVF	Y-detection by FISH	25	15 (60.0%)	Yan et al. [21]
Blastocysts	IVF	Y-detection by FISH	6	4 (66.7%)	Otsu et al. [22]
Zygotes	ICSI	Histone methylation patterns^a	10	10 (100%)	van der Heijden et al. [12]
Embryos	ICSI	Y-detection by FISH	6	1 (16.7%)	Sultan et al. [3]
Embryos	ICSI	Y-detection by FISH	17	6 (35.3%)	Staessen and van Steirteghem [7]
Embryos	ICSI	Y-detection by FISH	23	12 (52.2%)	Yan et al. [21]

aNote that this is a nongenetic method that distinguishes maternal and paternal chromatin independent of the occurrence of specific chromosomes. Under the assumption that X- and Y-spermatozoa participate equally in fertilization, the figures obtained by detection of a Y-chromosome should be doubled [9] and then yield percentages of heteroparental cells that are comparable to the findings of van der Heijden et al. [12].