Chromosome studies in 500 induced abortions

Defining ovarian reserve to better understand ovarian aging

Though a widely utilized term and clinical concept, ovarian reserve (OR) has been only inadequately defined. Based on Medline and PubMed searches we here define OR in its various components, review genetic control of OR, with special emphasis on the FMR1 gene, and discuss whether diminished OR (DOR) is treatable. What is generally referred to as OR reflects only a small portion of total OR (TOR), a pool of growing (recruited) follicles (GFs) at different stages of maturation. Functional OR (FOR) depends on size of the follicle pool at menarche and the follicle recruitment rate. Both vary between individuals and, at least partially, are under genetic control. The FMR1 gene plays a role in defining FOR at all ages. Infertility treatments have in the past almost exclusively only centered on the last two weeks of folliculogenesis, the gonadotropin-sensitive phase. Expansions of treatments into earlier stages of maturation will offer opportunity to significantly improve ovarian stimulation protocols, especially in women with DOR. Dehydroepiandrosterone (DHEA) may represent a first such intervention. Data generated in DHEA-supplemented women, indeed, suggest a new ovarian aging concept, based on aging of ovarian environments and not, as currently is believed, aging oocytes.

Investigation of chromosomal imbalance in human embryos using comparative genomic hybridization

Studies of cleavage-stage human embryos using fluorescence in-situ hybridization (FISH) to identify sub-sets of chromosomes have indicated that the incidence of chromosomal abnormalities is high. Whole genome amplification (WGA) and comparative genomic hybridization (CGH) to investigate the full chromosome complement applied to a small number of human embryos suggested an even higher rate of abnormality. WGA and CGH were used to identify genomic imbalance in individual blastomeres from human embryos, and the results were correlated with FISH analysis of sibling blastomeres. Forty embryos were analysed; 17 (42.5%) had a normal diploid karyotype and 23 (57.5%) were abnormal, with a chromosome imbalance in one or more cells including three (7.5%) that had a chaotic chromosome complement. Of the abnormal embryos, only three showed consistent aneuploidy. FISH results obtained from sibling blastomeres were in agreement with the CGH results in all 22 of the embryos where both tests were informative. It is concluded that rates of meiotic aneuploidy in human embryos may be lower than previous estimates. The results indicate that chromosomally abnormal embryos were more likely to have arisen as a result of cultural artefact or inadequate cell cycle surveillance, rather than meiotic error.

Chromosomal analysis in 894 induced abortuses from women of advanced maternal age in relation to gestational weeks and fetal sex ratio

OBJECTIVE

To clarify the prenatal sex ratio, and types and frequencies of chromosome anomalies in relation to gestational weeks in women of advanced maternal age.

METHODS

Chromosomal analysis was performed in 894 induced abortuses derived from elderly pregnant women 35 or more years of age.

RESULTS

The embryonic sex ratio in the chromosomally normal (abnormal) gave a preponderance of females over males in lower gestational weeks [366/458 (63/73); 79.9 to 100 (86.3 to 100) in 4-10 weeks]; the reversal of dominancy in those from females to males occurred in the 11th gestational week [41/29(5/4); 141.4 to 100 (125.0 to 100) in 11-20 weeks]. The frequency of trisomy in females at 10 weeks of gestation was significantly high (7/28; 25%).

CONCLUSIONS

This study showed that the existence of a difference of and a reversal of the sex ratio in gestational weeks. It was considered that there might be a lower viability of genetically handicapped males as compared to such females. However, the reversal of the sex ratio, such as that observed between 9th and 10th gestational weeks, might reflect events occurring after implantation.

Chromosomal studies on 934 induced abortuses of middle-aged pregnant women

A total of 934 induced abortuses of middle-aged pregnant women (35-48 years old) were chromosomally surveyed. The mean gestational age was 7.6 +/- 2.0 (S.D.) weeks after the first day of the last menstrual period, and the mean maternal age was 39.6 +/- 2.7 (S.D.) years. There was a high incidence of chromosomally abnormal fetuses in induced abortions, which markedly increased with the advancing age of the women: 9.6% (40/418) for the 35-39-year-old age group, 20.7% (100/484) for the 40-44-year-old age group, and 43.8% (14/32) for the 45-48-year-old age group, averaging 16.5%.

Effect of nitroxazepine on bone marrow cells of mice

The antidepressant drug, nitroxazepine, was tested in mice for mutagenicity in bone marrow cells by a micronucleus test. The drug was administered orally at a dose of 4.5, 9, and 13.5 mg per mouse. The results show that the drug is found to be mutagenic in mouse bone marrow cells.

A possibility of unbiased sex preselection in humans by enrichment of X or Y chromosome bearing spermatozoa

Human sex ratio is generally 1.06. The motility selected population of spermatozoa are usually Y chromosome rich. It is therefore easier to influence selected male births. Social and psychologic factors and economic needs intensified by high technology may cause further imbalance in the sex-ratio, creating a demand for techniques to influence sex selection. Such techniques may also help to handle sex linked defects. An examination of several studies on the sex chromosome distribution of human spermatozoa, based on HOP method, showed a preponderance of either X or Y bearing male pronuclei, depending on certain experimental conditions, indicating a technical possibility of influencing sex in an unbiased way.

Efficient direct chromosome analyses and enzyme determinations from chorionic villi samples in the first trimester of pregnancy

Chorionic villi were obtained by an aspiration technique which proved to be the best of four alternative procedures. We report in detail the series of experiments which led to (1) successful, rapidly growing cell cultures practically free of maternal cell contamination (the use of hormone-supplemented Chang medium greatly increased the growth rate); (2) an efficient direct method to obtain high quality metaphases from the Langhans cells of the cytotrophoblast tissue and with which the fetal karyotype is defined within a few hours of chorionic villi sampling; and (3) successful testing for the activity of eight enzymes directly from the villi samples, thus showing that this material is suitable for a rapid, direct diagnosis of the related metabolic diseases.

Low doses of X-rays decrease the risk of diploidy in mouse oocytes

Females from the NMRI/Han mouse strain ovulate a high number of diploid oocytes (about 12%) after gonadotrophin-stimulated ovulation. These oocytes can be fertilized and develop into triploid embryos subsequently. The exposure of such gonadotrophin-primed females to X-ray doses of 0.05, 0.10, 0.20 or 0.40 Gy during the preovulatory period (2 h after the HCG dose) significantly decreased the percentage of diploid oocytes. After the highest dose used, i.e. 0.80 Gy, however, the incidence was on the level from unirradiated females, again. We suggest that the observed negative hump-shaped dose response of diploidy is not caused by secondary modifications induced by irradiation, such as a selective killing of diploid oocytes before ovulation, or a (compensatory) super-ovulation of only normal oocytes, but rather is caused by a direct radiobiological interference of low doses in protecting from gonadotrophin-induced aneuploidy.

Causes of chromosome anomalies suggested by cytogenetic epidemiology of induced abortions

Women who visited hospitals requesting induced abortions were asked about their obstetric and medical histories by attending physicians prior to the operation. The information was solely based on their reports at the interview. The period of coverage was nine weeks, comprising six weeks before and three weeks after the onset of the last menstruation. Both the occurrence of acute respiratory infectious diseases, which included the common cold, upper respiratory tract infection (U.R.T.I.), influenza, and pneumonia, and the use of analgesics and antipyretics were most frequently reported. Regardless of whether they had an acute respiratory illness, the women who took analgesics and antipyretics (including antihistamine, cough remedy, and nasal decongestant) had 13.8% (8/58) gross chromosome anomalies. The women without the treatment had 6.3% (71/1136) anomalies. The difference was statistically significant (P less than 0.05). Triploid formation was particularly related to drug consumption, thus there were 5.2% (3/58) in the treated group and 0.5% (6/1136) in the untreated group (P=0.0074). In contrast, trisomy was not considered to be related to drug consumption on account of 8.6% (5/58) and 4.1% (47/1136) in the corresponding groups (0.10 less than P less than 0.20). When the occurrence of trisomy was examined in connection with two variables, i.e., the presence of drug consumption and the age of mothers, association was not evident (X2 assoc. = 0.883, d.f. = 1 by Cochran's method). Besides these results, neither maternal X-irradiation nor irregularity of the menstrual period was found to be related to the frequency of chromosome anomalies in the progeny.

Chromosome analysis of ectopic human conceptuses

Maternal factors (e.g. salpingitis) are known to be associated with ectopic gestations; however, few studies have considered the chromosomal complements or morphologic features of ectopic conceptuses. We studied 23 ectopic conceptuses removed from fallopian tubes during surgical resection. The chromosomal complements were normal (four with 46,XY; four with 46,XX) in all cases in which an intact embryo was identified, as well as in the single case characterized by disorganized embryonic tissue. Ten of the 14 ectopic conceptuses in which only a gestational sac and placental villi were identified also show normal chromosomal complements (seven with 46,XX; three with 46,XY); in the remaining four cases, variations from the normal chromosomal complement were found (46,XX/47,XX,+9; 45,X/46,XX; 46,XX/47,XX,+mar; and 92,XXXX). The former two probably signify underlying fetal abnormalities; however, the latter two could have reflected, respectively, in vitro aberrations or tetraploidy characteristic of normal amnion. Pooled data from this study and two previous reports indicate that ectopic conceptuses probable have no higher frequency of chromosomal abnormalities than in utero conceptuses of comparable embryonic ages.

Origin of mitotic cells of the chorionic villi in direct chromosome analysis

The origin of mitotic cells was investigated histologically in chorionic tissue, metaphase plates of which were used for direct cytogenetic study. Mitotic figures were often observed in the Langhans' cell layers, but absolutely none were seen in the syncytium and stromal cells.

Pre-implantation embryos of Chinese hamster. I. Incidence of karyotype anomalies in 226 control embryos

Karyotyes were determined in 226 pre-implantation embryos (4--8-cell stages) of Chinese hamster. The study was carried out under controlled natural breeding conditions, without superovulation and with the embryos developing in their mothers. A total of 5.3% karyotypically abnormal embryos were found. Over half, 3.1%, were due to ploidy mutations, 5 cases of triploidy and 2 cases of haploidy. Only 0.9% genome mutations were present, consisting of one autosomal trisomy and one autosomal monosomy. Structural aberrations were found in 1.8%, half of these probably due to a balanced maternal aberration and the rest appearing the mosaic condition only. These results are compared with the scarce body of mammalian data from the literature. Compared with the situation in man, the spontaneous aberration rates in the Chinese hamster and other experimental mammals are extremely low. This may be due, in part, to optimal timing of copulation in respect to estrus and ovulation prevailing in these animals but not in man. The low spontaneous aberration rate in the reported system is a valuable asset for purposes of mutagen testing.

The in vitro effects of imipramine on human chromosomes

The clastogenic effects of imipramine on chromosomes have been investigated in leukocyte cultures from seven healthy blood donors (2 mlae and 5 female), repeat cultures being initiated at intervals of 6 to 12 weeks. At various times prior to harvesting nine different doses of imipramine were added in vitro, the three lowest concentrations being within the range of plasma levels reported in psychiatric patients reveiving the drug therapeutically. In addition, streptonigrin was used as a positive control. No increase in chromosome breaks was found at any concentration for any duration of exposure even in those cultures where high concentration and/or long duration of exposure significantly suppressed cell growth. Only cultures to which streptonigrin had been added showed a significant increase in chromosome breaks.

[A further chromosome analysis in induced abortions (author's transl)]

The cytogenetic data of 500 unpublished cases of induced abortions are reported. The incidence of gross chromosome abnormalities was 7.4% (37/500). The frequencies of chromosome abnormalities after 6 gestational weeks decreased gradually with advancing the gestational weeks, while the frequency in the group of 5 gestational weeks remained considerably high as 25.0%.