Detection of aneuploidy for chromosomes 4, 6, 7, 8, 9, 10, 11, 12, 13, 17, 18, 21, X and Y by fluorescence in-situ hybridization in spermatozoa from nine patients with oligoasthenoteratozoospermia undergoing intracytoplasmic sperm injection.

Recent evidence suggests that infertile males donating semen for intracytoplasmic sperm injection (ICSI) may be at an increased risk of transmitting numerical (predominantly sex chromosome) abnormalities to their offspring. The present study was designed to determine aneuploidy in spermatozoa from oligoasthenoteratozoospermic (OAT) patients undergoing ICSI. Aneuploidy frequencies of 12 autosomes and the sex chromosomes were determined by fluorescence in-situ hybridization (FISH) on spermatozoa from fresh ejaculate of nine severe OAT patients and four proven fertile donors. FISH, using directly labelled (fluorochrome-dUTP) satellite or contig DNA probes specific for chromosomes 4, 6, 7, 8, 9, 10, 11, 12, 13, 17, 18, 21, X, and Y, was performed on decondensed spermatozoa. Per chromosome disomy frequencies for autosomes and sex chomosomes in OAT males were 0-5. 4%. In contrast, the disomy frequencies in controls were 0.05-0.2%. The frequency of diploid spermatozoa in OAT patients was 0.4-9.6%; controls showed a mean of 0.04%. Using recently developed formulae, the total aneuploidy in our OAT patient population was estimated to be 33-74%. In contrast, estimates of mean total aneuploidy in the spermatozoa of controls ranged from 4.1 to 7.7%, depending upon method of calculation. Six series of ICSI were performed on five of the OAT patients. Four resulted in no establishment of pregnancy; the others failed to establish ongoing pregnancies. Our cytogenetic data show significantly elevated frequencies of diploidy, autosomal disomy and nullisomy, sex chromosome aneuploidy, and total aneuploidy in OAT patients, which may contribute to the patients' infertility.     

Incidence of sperm chromosomal abnormalities in a risk population: relationship with sperm quality and ICSI outcome

BACKGROUND: An increased incidence of chromosome abnormalities has been reported in sperm samples of many infertile men by fluorescence in-situ hybridization (FISH). METHODS: Sperm aneuploidy and diploidy rates for chromosomes 13, 18, 21, X and Y were evaluated in 63 patients with normal karyotypes using dual and triple-colour FISH techniques. Indications for sperm FISH analysis were: recurrent miscarriages of unknown aetiology (RM, n = 40), repeated implantation failure after intracytoplasmic sperm injection (ICSI) (IF, n = 19), previous Down's syndrome pregnancies (n = 3), and meiotic abnormalities (MA, n = 1). Nine healthy normozoospermic donors were also evaluated as a control group. RESULTS: A significant increase in the incidence of sex chromosome disomies was found in the RM, IF and MA groups. Oligoasthenoteratozoospermic patients (n = 21) showed significantly higher rates of diploidy and disomies for sex chromosomes and chromosomes 18 and 21 than normozoospermic patients (n = 14). Thirty-one patients with normal and seven with abnormal FISH results had undergone several ICSI treatments (108 and 23 cycles respectively). Couples with abnormal sperm FISH results showed decreased pregnancy and implantation rates and increased miscarriage rates. CONCLUSIONS: Patients with a clinical background of recurrent miscarriages of unknown aetiology or implantation failure after ICSI are at risk of showing sperm chromosomal abnormalities, the incidence of which is higher in oligoasthenoteratozoospermic patients.     

Analysis of chromosomal abnormalities in human spermatozoa using multi-colour fluorescence in-situ hybridization

There is concern that intracytoplasmic sperm injection (ICSI) may lead to offspring with a high frequency of chromosomal abnormalities. Accordingly, we studied spermatozoa sampled from eight infertile men with oligoasthenoteratozoospermia (OAT) by multi-colour fluorescence in-situ hybridization (FISH), using DNA probes for chromosomes 13, 18, 21, X and Y. Results were compared with those of spermatozoa sampled from 10 healthy men with normal semen profiles. Analysis of the diploidy values was repeated twice in each of the 18 men. There was no significant difference in the two diploidy estimates; thus the FISH technique appeared to be accurate and reliable for determining aneuploidy in human spermatozoa. We found the average frequencies of disomy for chromosomes 13, 18, 21 and X or Y to be 0.13, 0.12, 0.24 and 0.59% respectively for the OAT group and 0.09, 0.13, 0.19 and 0.38% respectively for the control group. The diploidy rate was 0.29% in the OAT group, and 0.16% in the control group. Thus, the OAT group showed a significantly higher frequency of disomy for chromosomes 13 (P < 0.001), 21 (P < 0.05), sex (P < 0.001), and diploidy (P < 0.005) than the control group. This finding suggests there may be some risk of aneuploidy in the offspring conceived by the ICSI technique.     

Zusammenhang zwischen Spermiogrammparametern und chromosomalen Anomalien in Spermien

This study established a correlation between the aneuploidy and diploidy rates of the chromosomes 13, 16, and 21 in human germ cells, unsuccessful fertilization, and spermiogram parameters. Fluorescence in situ hybridization with two locus-specific probes for chromosomes 13 and 21 and a centromeric satellite probe for chromosome 16 was performed with special fixation techniques for sperm cells. One aim of the study was to prove whether there is a difference in the aneuploidy and diploidy frequencies between normospermic patients (normal motility and morphology of the sperm cells) and OAT patients (poor motility and morphology). The evaluation of 8000 sperms resulted in a significant difference (p=0.028) of the aneuploidy and diploidy rates in normospermic patients (0.9%) and OAT patients (1.2%). In order to examine this hypothesis, the second aim of this study was to determine the correlation between the frequency of aneuploidy and diploidy and the spermiogram parameters (motility and morphology) exactly. In this partial study we selected those spermatozoa that exhibited normal morphology and motility from the semen samples of OAT patients. We assessed the aneuploidy and diploidy frequencies and compared them with those in sperm cells of the same semen sample before the selection (0.9% vs 1.8%). Our results support the hypothesis of the positive correlation between abnormal sperm morphology or motility and their aneuploidy and diploidy rates.     

Correlation between semen parameters and sperm aneuploidy rates investigated by fluorescence in-situ hybridization in infertile men

Spermatozoa from 32 infertile patients and 13 controls with normal semen parameters were analysed using dual and triple colour fluorescence in-situ hybridization (FISH) techniques, in order to investigate the rates of aneuploidy for chromosomes 13, 18, 21, X and Y. The patients were divided into three groups according to their karyotypes or the karyotypes of their offspring: 15 were infertile men with abnormal semen parameters and normal karyotypes (group 1), 13 were infertile men with abnormal karyotypes and normal or abnormal semen (group 2) and four were infertile men with abnormal semen and normal karyotypes but whose wives conceived a child (or a fetus) with a numerical chromosomal abnormality through an intracytoplasmic sperm injection cycle (group 3). Patients with abnormal semen parameters showed a significantly higher aneuploidy rate for the investigated chromosomes in their spermatozoa compared to controls (P < 0.005). Our data suggest the presence of a correlation between poor semen parameters and an increase in aneuploidy rate of chromosomes 13, 18, 21, X and Y in spermatozoa (r = -0.81071, P < 0.002); therefore the risk of a chromosomal aneuploidy in spermatozoa seems to be inversely correlated to sperm concentration and total progressive motility. Patients with abnormal karyotypes showed a higher incidence of diploidy and chromosomal aneuploidies compared to controls (P < 0.002). This strongly suggests the presence of an interchromosomal effect of the cytogenetic rearrangement. Men who fathered a child with an abnormal karyotype through intracytoplasmic sperm injection did not present a higher aneuploidy rate for the investigated chromosomes in spermatozoa compared to patients with infertility due to a similar male factor but showed higher incidence of chromosomal aneuploidy compared to normal controls.     

Frequency of hyper-, hypohaploidy and diploidy in ejaculate, epididymal and testicular germ cells of infertile patients

The hypothesis that sperm aneuploidy and diploidy increase as a function of spermatogenesis impairment was addressed. Ejaculated semen samples from a series of men (n = 22) with very low total normal motile count (1 x 10(6)) was analysed in terms of sperm aneuploidy and diploidy by in-situ hybridization and compared with controls (n = 10). Germ cell aneuploidy was also analysed in an additional series of infertile patients presenting unexplained infertility (n = 3), congenital absence of the vas deferens (CAVD) (n = 6) and non-obstructive azoospermia (n = 3) undergoing IVF, microsurgical epididymal sperm aspiration (MESA)/ICSI and testicular sperm extraction (TESE)/ICSI cycles respectively. In-situ hybridization for chromosomes 1, 17, X and Y was performed on ejaculate, epididymal and testicular spermatozoa. Significantly higher sperm aneuploidy and diploidy rates where found (for the four chromosomes analysed) in spermatozoa from oligoasthenoteratozoospermia (OAT) over controls (18 versus 2.28% and 2.8 versus 0.13% respectively; P < 0.001). Testicular germ cells had even higher rates of sperm aneuploidy and diploidy. However, in this group it was difficult to determine whether the cells analysed were dysmorphic spermatozoa or spermatids. The data warrant further investigation on the cytogenetic abnormalities found in most germ cells identified in testicular tissue biopsies of azoospermic patients.     

Aneuploidy rate in spermatozoa of selected men with abnormal semen parameters

A large proportion of patients with oligoasthenoteratozoospermia (OAT) have an abnormal karyotype and hence they produce aneuploid gametes. However, a normal karyotype does not exclude the chance of having germ cell aneuploidy, since an altered intra-testicular environment not only damages spermatogenesis, but may also disrupt the mechanisms controlling chromosomal segregation during meiosis. Therefore, this study was undertaken to evaluate the rate of aneuploidy in the spermatozoa of selected patients with abnormal sperm parameters. For this purpose, sperm aneuploidy rate for chromosomes 8, 12, 18, X and Y was evaluated by multicolour fluorescence in-situ hybridization (FISH) in nine patients with teratozoospermia alone and 19 OAT patients of presumably testicular origin. Thirteen normozoospermic healthy men served as controls. Patients with teratozoospermia or OAT had significantly greater disomy and diploidy rates compared with controls, whereas the rate of nullisomy was similar. XY disomy was very low in all groups, suggesting that chromosomal non-disjunction occurs mainly during the second meiotic division. Autosome 12 disomy rate was low in both patients and controls. There was a marked variability of total sperm aneuploidy rate in both groups of patients. Sperm aneuploidy rate was negatively correlated with sperm concentration and particularly with the percentage of normal forms. In conclusion, patients with teratozoospermia or OAT have an increased rate of sperm aneuploidy. This increase is similar in both groups, suggesting that teratozoospermia may be the critical sperm parameter associated with aneuploidy.     

Intracytoplasmic sperm injection (ICSI) and chromosomally abnormal spermatozoa

An infertile couple was referred for intracytoplasmic sperm injection (ICSI) because of primary infertility and oligoasthenoteratozoospermia (OAT) in the male. It was observed that although the sperm cells presented with an unusual head size and multiple tails they were able to fertilize the oocytes after ICSI. Subsequent molecular cytogenetic analysis demonstrated de-novo chromosome abnormalities in virtually all sperm cells with 40% diploidy and 24% triploidy in addition to aneuploidy for the sex chromosomes.      

A detailed cytogenetic analysis of large numbers of fresh and frozen-thawed human sperm after ICSI into mouse oocytes

BACKGROUND: Since information about chromosome aberrations in micro-manipulated sperm is still inadequate, cytogenetic analysis was performed on large numbers of fresh and frozen-thawed (FT) human sperm after injection into mouse oocytes. The effects of the ICSI procedure on oocytes are also discussed based on analysis of the mouse chromosome complements. METHODS: After the injection of fresh and FT human sperm into mouse oocytes, chromosomes of the hybrid oocytes were analysed at first cleavage metaphase. RESULTS: Incidences of the hybrid oocytes at the first cleavage metaphase were significantly different between fresh (71.5%) and FT sperm groups (80.1%) (P < 0.05). The chromosome analysis of 477 fresh and 141 FT sperm showed no difference in the incidences of aneuploidy (1.6/0.7%), structural aberrations (8.8/7.8%) or diploidy (0.0/0.0%) between these categories. The cytogenetic result did not differ from our previous result using IVF between human sperm and hamster oocytes. In an additional cytogenetic study on 615 mouse chromosome complements, the incidence of diploidy (5.4%) was significantly higher than those (0.3-2.8%) in the previous mouse cytogenetic studies, and the hybrid oocytes with no mouse chromosomes (2.0%) existed. CONCLUSIONS: This result suggests that the ICSI procedure induces no sperm chromosome aberrations but increases numerical aberrations in oocyte chromosome complements.     

High sperm aneuploidy rate in unselected infertile patients and its relationship with intracytoplasmic sperm injection outcome.

BACKGROUND: Men with oligoasthenoteratozoospermia (OAT) frequently undergo intracytoplasmic sperm injection (ICSI) as a treatment for their infertility. However, there is an increased risk of transmitting chromosomal abnormalities to the offspring given that natural selection is bypassed by the use of this technique and patients have an increased rate of sperm aneuploidy which, in addition, may negatively affect ICSI outcome. For this reason, the rate of sperm aneuploidy in unselected patients undergoing ICSI and its impact on ICSI performance have been evaluated. METHODS: Aneuploidy and diploidy were evaluated in spermatozoa separated by swim-up for oocyte injection, using DNA probes for chromosomes 8, 12, 18, X and Y. RESULTS: ICSI patients had sperm aneuploidy and diploidy rates significantly higher than those of 13 normozoospermic men who served as controls. Although the total aneuploidy rate varied considerably between the 18 patients, 15 of them (83%) had values above the upper range of the control group. Eighteen ICSI cycles were performed with an overall fertilization rate of 95% and a pregnancy rate of 39%. The aneuploidy rate of the 11 patients whose wives did not achieve pregnancy was slightly higher than that of pregnant couples, but the difference did not reach statistical significance. However, 10 patients in this group (91%) had a sperm aneuploidy rate well above the upper limit of the controls as compared with two patients in the "pregnant" group (29%). CONCLUSIONS: This study has shown that unselected patients undergoing ICSI had an elevated sperm aneuploidy rate. Lack of pregnancy was associated with a tendency towards an increased aneuploidy rate; however, pregnancy occurred even in the presence of an elevated sperm aneuploidy rate.     

Globozoospermia is associated with chromatin structure abnormalities: case report

A recent study has shown normal sperm chromatin structure in a patient with globozoospermia. However, the poor success rate following intracytoplasmic sperm injection (ICSI) with the use of this sperm suggests that sperm nuclear abnormalities may be present. We report here a study of the sperm DNA integrity and chromosome aneuploidy and diploidy rates of a patient with 100% round-headed sperm. The sperm chromatin packaging quality was assessed by using flow cytometry after staining the DNA with propidium iodide. DNA fragmentation, possibly indicative of apoptosis, was evaluated by flow cytometry using the terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick-end labelling (TUNEL) assay. The sperm chromosome aneuploidy and diploidy rates were evaluated by fluorescence in-situ hybridization using alpha-centromeric probes for chromosomes 8, 12, 18, X and Y. The patient with globozoospermia had a significantly higher number of sperm with chromatin decondensation (35 +/- 1.1%) and positive for the TUNEL assay (37 +/- 1.7%) compared with that found in four normal controls (4.7 +/- 0.4 and 22.5 +/- 1.2% respectively). In contrast, the total sperm aneuploidy (0.16%) and diploidy (0.05%) rates for the chromosomes studied were within the range found in 14 normozoospermic men. To the best of our knowledge, this is the first case report of round-headed sperm that has shown an elevated number of sperm with abnormal chromatin structure and DNA strand breaks.     

Frequency of aneuploidy in sperm from patients with extremely severe male factor infertility

BACKGROUND: A protocol for the chromosomal analysis of sperm samples with a severely reduced number of sperm cells was designed. METHODS: A severe male factor condition was the main cause of infertility for 38 couples: 27 were oligoasthenoteratospermic (OAT) and 11 with non-obstructive azoospermia underwent testicular sperm extraction (TESE). A two-round fluorescence in situ hybridization (FISH) protocol was performed with probes specific for the chromosomes X, Y, 13, 15, 16, 17, 18, 21 and 22. The recording of the position of each sperm cell at the microscope allowed diagnosis of each spermatozoon for the nine tested chromosomes. RESULTS: A mean number of 122+/-78.5 sperm were diagnosed per patient with an incidence of total abnormalities corresponding to 13.4%. chi2-tests for the observed frequencies and goodness-of-fit test were highly significant in all cases. A significantly higher proportion of total aneuploidy was detected in 79% of the tested samples compared to the normal population. Testicular sperm were significantly more prone to aneuploidy than ejaculated sperm. CONCLUSIONS: The designed FISH protocol for the analysis of severe OAT and TESE sperm samples is reliable, implying that the studied sample is representative of the original population. In view of the high incidence of aneuploidy in most severe OAT and TESE sperm, the FISH analysis of pathological sperm samples can be routinely performed in order to estimate the chances of the paternal contribution to aneuploidy in the resulting embryos.     

Morphologically normal spermatozoa of patients with secretory oligo-astheno-teratozoospermia have an increased aneuploidy rate

BACKGROUND: Normal morphology is a major criterion for selecting spermatozoa to be injected. Given that teratozoospermia is one of the most critical parameters associated with sperm aneuploidy, the purpose of this study was to evaluate the aneuploidy rate of morphologically normal spermatozoa of patients with oligo-astheno-teratozoospermia (OAT). METHODS: Ten patients with secretory OAT and six age-matched normozoospermic men with a normal karyotype were enrolled. After assignment to normal or abnormal category, the location of each spermatozoon was recorded using an electronic microstage locator. Slides were then subjected to triple-colour fluorescence in situ hybridization for chromosomes X, Y and 12. RESULTS: OAT patients had a lower number of morphologically normal and abnormal spermatozoa carrying the X chromosome, compared with normozoospermic men. They also exhibited increased XY and XX disomy rates. Morphologically abnormal spermatozoa from normozoospermic men also had an increased XX disomy rate compared with normally shaped spermatozoa obtained from the same men. The total sperm aneuploidy rate of morphologically abnormal spermatozoa of normozoospermic men was 4.4-fold higher than that of spermatozoa with normal morphology. The total aneuploidy rates of spermatozoa with normal or abnormal head shape from OAT patients were similar to each other and to that of abnormally shaped spermatozoa from normozoospermic men, but they were higher than the rate found in normally shaped spermatozoa of normal men. CONCLUSIONS: Normally shaped spermatozoa of OAT patients have an increased aneuploidy rate.     

Polyploidy in large-headed sperm: FISH study of three cases

BACKGROUND: Macrocephalic or large headed sperm with multiflagella is a rare abnormality often associated with infertility. Sperm chromosomal abnormalities could be associated with this specific morphological abnormality. METHODS: The cytogenetic content of large-headed sperm was assessed by dual and three-colour fluorescence in-situ hybridization in three patients carrying this specific morphological abnormality. RESULTS: In all patients nearly all sperm contained at least one copy of each sex chromosome, and in more than half of them at least two copies of either chromosome 1 or 18 were identified. In some sperm a tetraploidy was found. CONCLUSIONS: These observations suggested that both meiotic I and II divisions were affected by incomplete partition of homologous chromosomes during meiosis I and of sister chromatids during meiosis II associated with a failure of nuclear cleavage. Furthermore, they provide evidence for a clear relationship between a specific morphological abnormality of the sperm and their abnormal cytogenetic content. The treatment of infertility using ICSI would probably be unsuccessful and have a high genetic risk in these cases.     

Incidence of aneuploid spermatozoa from subfertile men: selected with motility versus hemizona-bound

Spermatozoa-zona pellucida binding selects for human spermatozoa with progressive motility, normal morphology and functional competency. We postulated that this gamete interaction would also act to select against spermatozoa with chromosomal numerical aberrations. Spermatozoa from 41 men participating in the intracytoplasmic sperm injection (ICSI) programme were evaluated for the incidence of aneuploidy of chromosomes 18, X and Y. The hemizona assay was utilized to determine whether zona-bound spermatozoa from these patients have a reduced incidence of aneuploidy compared with those selected by motility only in a standard swim-up procedure. Using multicolour fluorescence in-situ hybridization (FISH) with DNA probes specific for chromosomes 18, X and Y, the disomy rates for chromosomes 18, X, Y and XY were found to be 0.31, 0.27, 0.29 and 0. 14% respectively in the swim-up motile fraction, and 0.31, 0.33, 0. 32 and 0.19% respectively in the pellet fraction. Analysing the zona-bound spermatozoa, the disomy rates for chromosome 18, X, Y and XY were found to be 0.02, 0.15, 0.12 and 0.07% respectively. The zona-bound spermatozoa had a significantly lower frequency of aneuploidy than the swim-up motile fraction or the pellet fraction (P < 0.0001). The incidence of chromosome 18 aneuploidy, including both chromosome 18 disomy and nullisomy, in the swim-up motile fractions was significantly increased in patients with an abnormal or borderline hemizona index compared with those with a normal hemizona index (P < 0.05). We also found that a high incidence of sperm aneuploidy was associated to a certain extent with low fertilization rate, and with failure to achieve pregnancy through ICSI. This study suggests that the human zona pellucida has the capacity to select against aneuploid spermatozoa by an as yet undetermined mechanism.     

Chromosome analysis of epididymal and testicular sperm in azoospermic patients undergoing ICSI

BACKGROUND: Although ICSI provides a way of treating azoospermic men, concern has been raised about the potential risk for transmission of genetic abnormalities to the offspring. We quantified the incidence of chromosomal abnormalities in epididymal and testicular sperm retrieved from azoospermic patients undergoing ICSI. METHODS: Individual testicular sperm were collected from testicular biopsies with an ICSI pipette, and epididymal sperm were retrieved by microsurgical epididymal sperm aspiration. Samples were processed by fluorescent in-situ hybridization (FISH) for chromosomes 18, 21, X and Y and the results compared with those from normal ejaculated samples. RESULTS: The overall aneuploidy rate of 11.4% in men with non-obstructive azoospermia was significantly higher (P = 0.0001) than the 1.8% detected in epididymal sperm from men with obstructive azoospermia and also the 1.5% found in ejaculated sperm. No significant difference was found between the epididymal and ejaculated samples. When the chromosomal abnormalities were analysed, gonosomal disomy was the most recurrent abnormality in both obstructive and non-obstructive azoospermic patients, while autosomal disomy was the most frequent in ejaculated sperm. CONCLUSIONS: Sperm of non-obstructive azoospermic men had a higher incidence of chromosomal abnormalities, of which sex chromosome aneuploidy was the most predominant. Genetic counselling should be offered to all couples considering infertility treatment by ICSI with testicular sperm.     

Sperm aneuploidy and meiotic sex chromosome configurations in an infertile XYY male

BACKGROUND: There is little information regarding the behaviour of the extra Y chromosome during meiosis I in men with 47,XYY karyotypes and the segregation of the sex chromosomes in sperm. We applied immunofluorescent and FISH techniques to study the relationship between the sex chromosome configuration in meiotic germ cells and the segregation pattern in sperm, both isolated from semen samples of a 47,XYY infertile man. METHODS: The sex chromosome configuration of pachytene germ cells was determined by immunostaining pachytene nuclei for synaptonemal complex protein 3 (SCP3) and SCP1. FISH was subsequently performed to identify the sex chromosomes and chromosome 18 in pachytene cells. Dual- and triple-color FISH was performed on sperm to analyse aneuploidy for chromosomes 13, 18, 21, X, and Y. RESULTS: 46,XY/47,XYY mosaic pachytene cells were observed (22.2% vs. 77.8%, respectively). The XYY trivalent, and X+YY configurations were most common. While the majority of sperm were of normal chromosomal constitution, an increase in sex and autosome disomy was observed. CONCLUSIONS: The level of germ cell moscaicism and their meiotic sex chromosome configurations may determine sperm aneuploidy rate and fertility status in 47,XYY men. Our approach of immunostaining meiotic cells in the ejaculate is a novel method for investigating spermatogenesis in infertile men.     

FISH analysis of chromosome X,Y and 18 abnormalities in testicular sperm from azoospermic patients

BACKGROUND: Sperm extracted from testicular biopsies of azoospermic men can successfully be used for ICSI. The concern exists that testicular sperm from azoospermic men suffering from severe testicular failure may have a higher frequency of aneuploidy, which may lead to an increased risk for chromosomally abnormal offspring. METHODS: Testicular sperm from patients showing spermatogenic failure (n = 17) and from patients with normal spermatogenesis (n = 26) were analysed by fluorescence in-situ hybridization (FISH). Numerical chromosomal abnormalities for chromosomes X, Y and 18 were evaluated by FISH in a total of 1697 testicular sperm derived from 43 azoospermic patients. RESULTS: No difference was observed between the frequency of chromosomal abnormalities in testicular sperm from patients with normal spermatogenesis (5.6%) and from patients with spermatogenic failure (8.2%). However, the frequency of aneuploidy for chromosome 18 was higher in the group of azoospermic patients with spermatogenic failure than in the group with normal spermatogenesis (3.2 versus 1.3%). Within the obstructive group, sex chromosome aneuploidy (4.5%) occurred more frequently than chromosome 18 aneuploidy (1.3%; P < 0.001). Among testicular sperm derived from patients with spermatogenic failure, sex chromosomal aneuploidy (5.8%) was similar to that for chromosome 18 (3.2%). CONCLUSIONS: So far, no difference in the total frequency of chromosomal abnormalities has been observed between patients with normal spermatogenesis and patients with severe testicular failure. However, aneuploidy for chromosome 18 was higher in the group with spermatogenic failure.     

Chromosome analysis of spermatozoa extracted from testes of men with non-obstructive azoospermia

Infertile men with azoospermia now have the possibility of fathering children by testicular sperm extraction combined with intracytoplasmic sperm injection. However, there are concerns about the risk of chromosomal abnormalities in their spermatozoa. We have studied aneuploidy frequencies for chromosomes 13, 21, X and Y by multicolour fluorescence in-situ hybridization (FISH) in testicular spermatozoa extracted from three men with non-obstructive azoospermia. The men were 34-37 years of age and had normal follicle-stimulating hormone (FSH) concentrations and normal 46,XY somatic karyotypes. A total of 3324 spermatozoa was analysed. The infertile patients had an elevated frequency of disomy for chromosomes 13, 21, XY disomy compared to controls but none of these reached statistical significance. Also there was no significant difference in the sex ratio or the frequency of diploidy in azoospermic patients compared to normal control donors. This first report on chromosomal aneuploidy in spermatozoa extracted from testes of patients with non-obstructive azoospermia suggests that some azoospermic men do not have a substantially increased risk of chromosomally abnormal spermatozoa.     

Fertilization and early embryology: Cytogenetic and fluorescent in-situ hybridization chromosomal studies on in-vitro fertilized and intracytoplasmic sperm injected 'failed-fertilized' human oocytes

This study was undertaken to establish baseline data on thechromosomal status of ‘failed-fertilized’ oocytesderived from in-vitro fertilization (IVF) or intracytoplasmicsperm injection (ICSI) procedures. A cytogenetic analysis wasundertaken on 162 IVF and 51 ICSI oocytes. In all, 82.1% (133/162)of the IVF and 78.4% (40/51) of the ICSI oocytes had metaphaseII (Mil) plates, of which 50.4% of the IVF and 47.5% of theICSI oocytes were analysed further. Chromosomes of the G-group(21–22) were identified with the majority of the anomalies.No overall significant difference in the aneuploidy rate wasfound for the IVF (37.3%) or ICSI (31.6%) oocytes, or with maternalage. However, chromosome anomalies, e.g. diploidy, fragmentedand broken chromatids, single sperm and oocyte chromatids, werefound in oocytes from IVF patients aged >36 years and inthe ICSI oocytes throughout the maternal age range (31–38years). The status of the polar body chromatin indicated thatthere was no overall significant difference in the maturationof the IVF and ICSI oocytes. Evidence of successful sperm deliverywas found in 72.5% (37/51) of the ICSI failed-fertilized oocytes.In this group there was a significant increase in the incidenceof premature chromosome condensation: 19.6% (10/51) containedsperm chromosomes, 7.8% (4/51) had swollen sperm heads, andthe remaining 45.0% had condensed sperm heads. The presenceof both sperm and Mil oocyte chromosomes was found in 19.6%(10/51) of the ICSI and 8.6% (14/162) of the IVF failed-fertilizedoocytes. Specific fluorescent in-situ hybridization DNA probeswere used to re-analyse the chromosomes of karyotyped ‘failed-fertilized’IVF oocytes and, for the first time, applied to the karyotypedchromosomes of failed-fertilized ICSI oocytes. The hybridizationefficiency was 86–95% for the centromere probe and 100%for probes 21 and 18.