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During in-vitro fertilization (IVF) procedures, human preimplantation embryos were classified into four grades according to their morphological appearance under light microscopy. The grade IV group included poor quality embryos. In our IVF programme, these embryos were never transferred or frozen, and were thus available for cytogenetic analysis. Cytogenetic analysis was performed on 411 grade IV embryos from 327 couples participating in the IVF programme. A total of 118 embryos were successfully karyotyped using at least one metaphase. Normal diploid chromosomes were found in only 12 embryos, containing a total of 19 metaphases. All others (90%) showed abnormal or aberrant chromosome complements; 48 were aneuploid and six cases of single chromatids were noted; 14 embryos (11.8%) contained haploid complements, while the remaining 44 exhibited mosaics (2n/3n, n/2n, n/3n) or fragmented chromosome sets. Also, several structural aberrations and rearrangements were observed. These results indicate that the large majority of grade IV human embryos are chromosomally abnormal. This confirms the morphological assessment of the poor quality of these embryos and demonstrates the uselessness of both the transfer and the cryopreservation of grade IV embryos. [ABSTRACT FROM AUTHOR]

The cytogenetic study of human gametes is a new and important source of information because most chromosomal abnormalities originate from meiotic disorders. The frequency and type of abnormalities were analysed in both spermatozoa and mature oocytes. A total of 13,975 human sperm chromosome complements and 1897 oocyte chromosome complements were analysed. In the present study, pooled cytogenetic data on human gametes have been examined to determine and compare the distribution of non-disjunctions in male and female gametes. Human spermatozoa are characterized by a significant excess of hypohaploidy and an equal distribution of aneuploidies among all chromosome groups, whereas mature oocytes display an equal ratio of hypohaploidy to hyperhaploidy and a high variability in the distribution of non-disjunction: in particular, there is a significant over-representation of aneuploidies in both D and G chromosome groups. This indicates that non-disjunction is not a random event in female meiosis and, consequently, that there are differences in the meiotic process between the sexes. Meiotic and environmental factors which could explain the non-random malsegregation of chromosomes in female meiosis are discussed. The role of maternal age as a cause of aneuploidy is questioned. [ABSTRACT FROM AUTHOR]

Duplications of chromosome 16p are often the products of unbalanced maternal reciprocal translocations and consequently the phenotype of patients is not typical of pure partial trisomy 16p. R-banding and fluorescence in situ hybridization (FISH) in our patients were in favour of de novo pure partial trisomy of 16p. Furthure clinical and paraclinical analysis of our three cases in addition to a review of literature and analysis of published clinical and cytogenetic data on five cases of pure partial duplications of chromosome 16p reported until now lead to the delineation of three groups of duplications. Patients with short proximal 16p11~p12 euchromatic duplication considered as "silent" duplication and no clinical anomaly are included in the first group. The second group with a larger 16p11-p12~p13 duplication is caracterised by a particular phenotype including severe mental retardation, dysmorphism, variable malformations and recurrent infections. The third group has terminal 16p13-pter duplication and is not well defined to date. Based on our cases and reported cases of pure partial trisomy of 16p in the literature we propose diagnostic measures in case of an elongated 16p chromosome encountered in prenatal chromosome analysis.