Human Sperm Chromosomes Research Articles

Human Sperm Chromosomes: To Form Hairpin-Loops, Or Not to Form Hairpin-Loops, That Is the Question.

Background: Genomes are non-randomly organized within the interphase nucleus; and spermatozoa are proposed to have a unique hairpin-loop configuration, which has been hypothesized to be critical for the ordered exodus of the paternal genome following fertilization. Recent studies suggest that the hairpin-loop model of sperm chromatin organization is more segmentally organized. The purpose of this study is to examine the 3D organization and hairpin-loop configurations of chromosomes in human spermatozoa. Methods: Three-color sperm-fluorescence in-situ hybridization was utilized against the centromeres, and chromosome p- and q-arms of eight chromosomes from five normozoospermic donors. Wide-field fluorescence microscopy and 3D modelling established the radial organization and hairpin-loop chromosome configurations in spermatozoa. Results: All chromosomes possessed reproducible non-random radial organization (p < 0.05) and formed discrete hairpin-loop configurations. However, chromosomes preferentially formed narrow or wide hairpin-loops. We did not find evidence to support the existence of a centralized chromocenter(s) with centromeres being more peripherally localized than one or both of their respective chromosome arms. Conclusion: This provides further evidence to support a more segmental organization of chromatin in the human sperm nucleus. This may be of significance for fertilization and early embryogenesis as specific genomic regions are likely to be exposed, remodeled, and activated first, following fertilization.

Research on the Vertical Transmission of Hepatitis C Gene from Father-to-child via Human Sperm.

The aim was to develop a better experimental model which could facilitate further studies assessing the vertical HCV gene transmission via human spermatozoa, and verify the possibility of father-to-child transmission of the HCV gene. The recombinant plasmid pIRES2-EGFP-HCV C was constructed. Fluorescence in situ hybridization was performed to detect the integration of the HCV C gene in human sperm genome and in zygote's pronucleus. Successful construction of recombinant plasmid pIRES2-EGFP-HCV C was confirmed by restriction mapping, PCR, and sequencing. Positive HCV C DNA signals were observed in sperm heads, human sperm chromosomes and two-cell embryos in transfected samples. No positive signal was found in normal control and HCV infected groups. The recombinant plasmid pIRES2-EGFP-HCV C was successfully constructed. The HCV C gene was able to pass through the sperm membrane and integrate into the sperm genome. Human sperm carrying the HCV C gene was able to achieve normal fertilization. The replication of the sperm-mediated HCV C gene was synchronized with that of the host genome. Our results provide direct evidence for vertical transmission of the HCV C gene from father-to-child via human sperm.

Hierarchical radial and polar organisation of chromosomes in human sperm

It is well established that chromosomes occupy distinct positions within the interphase nuclei, conferring a potential functional implication to the genome. In addition, alterations in the nuclear organisation patterns have been associated with disease phenotypes (e.g. cancer or laminopathies). The human sperm is the smallest cell in the body with specific DNA packaging and the mission of delivering the paternal genome to the oocyte during fertilisation. Studies of nuclear organisation in the sperm have postulated nonrandom chromosome position and have proposed a chromocentre model with the centromeres facing toward the interior and the telomeres toward the periphery of the nucleus. Most studies have assessed the nuclear address in the sperm longitudinally predominantly using centromeric or telomeric probes and to a lesser extent with whole chromosome paints. To date, studies investigating the radial organisation of human sperm have been limited. The purpose of this study was to utilise whole chromosome paints for six clinically important chromosomes (18, 19, 21, 22, X, and Y) to investigate nuclear address by assessing their radial and longitudinal nuclear organisation. A total of 10,800 sperm were analysed in nine normozoospermic individuals. The results have shown nonrandom chromosome position for all chromosomes using both methods of analysis. We present novel radial and polar analysis of chromosome territory localization within the human sperm nucleus. Specifically, a hierarchical organisation was observed radially with chromosomes organised from the interior to the periphery (chromosomes 22, 21, Y, X, 19, and 18 respectively) and polar organisation from the sperm head to tail (chromosomes X, 19, Y, 22, 21, and 18, respectively). We provide evidence of defined nuclear organisation in the human sperm and discuss the function of organisation and potential possible clinical ramifications of these results in regards to male infertility and early human development.

The Integrated HIV-1 Provirus in Patient Sperm Chromosome and Its Transfer into the Early Embryo by Fertilization

Complete understanding of the route of HIV-1 transmission is an important prerequisite for curbing the HIV/AIDS pandemic. So far, the known routes of HIV-1 transmission include sexual contact, needle sharing, puncture, transfusion and mother-to-child transmission. Whether HIV can be vertically transmitted from human sperm to embryo by fertilization is largely undetermined. Direct research on embryo derived from infected human sperm and healthy human ova have been difficult because of ethical issues and problems in the collection of ova. However, the use of inter-specific in vitro fertilization (IVF) between human sperm and hamster ova can avoid both of these problems. Combined with molecular, cytogenetical and immunological techniques such as the preparation of human sperm chromosomes, fluorescent in situ hybridization (FISH), and immunofluorescence assay (IFA), this study mainly explored whether any integrated HIV provirus were present in the chromosomes of infected patients' sperm, and whether that provirus could be transferred into early embryos by fertilization and maintain its function of replication and expression. Evidence showed that HIV-1 nucleic acid was present in the spermatozoa of HIV/AIDS patients, that HIV-1 provirus is present on the patient sperm chromosome, that the integrated provirus could be transferred into early embryo chromosomally integrated by fertilization, and that it could replicate alongside the embryonic genome and subsequently express its protein in the embryo. These findings indicate the possibility of vertical transmission of HIV-1 from the sperm genome to the embryonic genome by fertilization. This study also offers a platform for the research into this new mode of transmission for other viruses, especially sexually transmitted viruses.

Kinetics of human male pronuclear development in a heterologous ICSI model

To evaluate human sperm nuclear chromatin decondensation in a heterologous ICSI system using hamster ova injected with human sperm. Frozen hamster oocytes were injected with Triton X-100 treated sperm and fixed at different time points post ICSI. Oocytes injected with non-treated sperm served as controls. Male pronuclear decondensation was evaluated after staining with DAPI. Sperm cells with partially destroyed membranes and depletion of the acrosome decondense more rapidly and to a greater extent than membrane/acrosome intact cells. Marked variability in pronuclear size was observed for any time point post ICSI, which most probably reflects the heterogeneity in the mature human sperm population. Remodeling of male gamete nuclei in this heterologous ICSI mimics events that occur during natural fertilization in humans and therefore this approach may be used for studies of human sperm chromosomes transformations.

Reorganisation of human sperm nuclear architecture during formation of pronuclei in a model system

By fertilisation, two terminally differentiated cells, namely the egg and spermatozoon, are combined to create a totipotent zygote. During this process, the inactive sperm nucleus is transformed into a functional male pronucleus. Recent studies demonstrate that human sperm chromatin has an elaborate multilevel organisation, but almost nothing is known about how sperm chromosomes are transformed during fertilisation. Because of ethical reasons and technical complications, experimentation with human embryos is generally unworkable and adequate model systems are necessary to study the formation of male pronuclei. Here, we analyse remodelling of human sperm chromatin and chromosome architecture in Xenopus egg extracts using immunofluorescent localisation of protamines and centromere protein A, as well as fluorescence in situ hybridisation localisation of major alpha-satellite DNA and whole chromosome territory (CT). We demonstrate noticeable relocalisation of centromeres and remodelling of CT during the decondensation-recondensation cycle, mimicking cellular events that occur in the paternal genome in vivo during fertilisation.

Chromosome distribution in human sperm – a 3D multicolor banding-study

BackgroundNuclear architecture studies in human sperm are sparse. By now performed ones were practically all done on flattened nuclei. Thus, studies close at the in vivo state of sperm, i.e. on three-dimensionally conserved interphase cells, are lacking by now. Only the position of 14 chromosomes in human sperm was studied.ResultsHere for the first time a combination of multicolor banding (MCB) and three-dimensional analysis of interphase cells was used to characterize the position and orientation of all human chromosomes in sperm cells of a healthy donor. The interphase nuclei of human sperm are organized in a non-random way, driven by the gene density and chromosome size.ConclusionHere we present the first comprehensive results on the nuclear architecture of normal human sperm. Future studies in this tissue type, e.g. also in male patients with unexplained fertility problems, may characterize yet unknown mechanisms of infertility.

Organization of chromosomes in spermatozoa: an additional layer of epigenetic information?

Elaborate non-random organization of human sperm chromosomes at different structural levels, starting from the DNA packing by protamines up to the higher-order chromosome configuration and nuclear positioning of chromosome territories, has been discovered. Here, we put forward a hypothesis that the unique genome architecture in sperm provides a mechanism for orchestrated unpacking and ordered activation of the male genome during fertilization, thus offering an additional level of epigenetic information that will be deciphered in the descendant cells.

Meiotic segregation analysis in male translocation carriers by using fluorescent in situ hybridization

Balanced reciprocal and Robertsonian translocations are the most common structural chromosome abnormalities in humans, with incidences of 0.7 and 1.23 per 1000. These translocations can affect fertility and/or pregnancy outcome because of possibly impaired production of gametes with an unbalanced zygote caused by the parental arrangement. Fertility problems in male translocation carriers are because of various degrees of sperm alterations that are directly related to the disturbance of the meiotic process. Investigation of human sperm chromosomes was performed by karyotyping spermatozoa after penetration of zona-free hamster oocytes, karyotype analysis now being possible to analyse the segregation patterns by using fluorescent in situ hybridization (FISH). Here, we document the results of meiotic segregation analysis for four Robertsonian and four reciprocal translocation carriers by FISH. In the sperm of Robertsonian translocation males, the majority of spermatozoa were normal/balanced. On the other hand, males with reciprocal translocations demonstrated a high rate of unbalanced spermatozoa of about 50% on meiotic segregation, with an unusually high rate (23.5%) of 3 : 1 segregation. This knowledge can be used for genetic counselling of families with these types of translocations.

Visualization of human sperm chromosomes by using mouse oocytes cryothawed after enucleation

To evaluate whether previously enucleated mouse oocytes that are vitrified are usable for the analysis of human sperm chromosomes. Prospective, comparative laboratory study. Animal breeding and reproduction department in a rural Japan university. Sperm samples were obtained from a fertile donor. Human sperm were injected into previously enucleated-vitrified mouse oocytes. The rates of appearance of the human sperm chromosomes that were injected into previously enucleated-vitrified mouse oocytes. The rates of appearance of human sperm chromosomes were 71%-72% in enucleated-vitrified mouse oocytes. The use of enucleated-vitrified mouse oocytes allowed visualization of human sperm chromosomes.

A novel method for chromosome analysis of human sperm using enucleated mouse oocytes

Mouse oocytes can be used in conjunction with intracytoplasmic sperm injection (ICSI) as a technique to permit chromosomal analysis of human sperm. However, chromosomes derived both from the human sperm and the mouse oocyte appear simultaneously following ICSI. The present study focused on evaluating whether or not previously enucleated mouse oocytes are usable for the analysis of human sperm chromosomes. The metaphase chromosome-spindle complex was removed from a mouse oocyte. Human sperm from a donor with proven fertility were injected into mouse enucleated oocytes or intact oocytes. The presence of pronuclei in the oocytes was confirmed approximately 7-11 h after ICSI, and the oocytes were then fixed so that the nuclei could be observed as chromosome samples at 15-16 h after ICSI. The formation rate of one pronucleus in enucleated oocytes after ICSI was 93.9% (186/198) while that of two pronuclei in intact oocytes after ICSI was 85.4% (88/103). The appearance rate of metaphase chromosomes of human sperm in the enucleated oocytes, 89.4% (160/179), was significantly higher than that in intact oocytes, 78.7% (74/94) (P = 0.017). An efficient ICSI method using enucleated mouse oocytes was established to allow the visualization of the human sperm chromosome complement without the risk of confusion with mouse oocyte chromosomes.

Meiotic segregation of translocations during male gametogenesis.

Balanced reciprocal and Robertsonian translocations are the most common structural chromosomal abnormalities in humans. Generally, they are without consequence for the carrier, but for various degrees of oligoasthenoteratozoospermia in men. As these carriers can produce a significant percentage of gametes with an unbalanced combination of the parental rearrangement, there is a more or less significant risk, according to cases, of chromosomal imbalances for their offspring. Therefore, techniques were developed to study the meiotic segregation of these translocations in males. Direct investigation of human sperm chromosomes became possible by karyotyping spermatozoa after penetration of zona-free hamster oocytes and, more recently, using fluorescent in situ hybridization (FISH). This paper reviews the results obtained using these techniques in Robertsonian and reciprocal translocations. The studies on spermatozoa from translocation carriers help the comprehension of the mechanisms of the meiotic segregation. They should be integrated in the genetic exploration of the infertile men, in order to give them a personalized risk assessment of unbalanced spermatozoa, specially as a correlation was found recently between the percentage of abnormal spermatozoa and that of abnormal embryos.

Effects of hepatitis B virus infection on human sperm chromosomes.

To evaluate the level of sperm chromosome aberrations in male patients with hepatitis B, and to directly detect whether there are HBV DNA integrations in sperm chromosomes of hepatitis B patients. Sperm chromosomes of 14 tested subjects (5 healthy controls, 9 patients with HBV infection, including 1 with acute hepatitis B, 2 with chronic active hepatitis B, 4 with chronic persistent hepatitis B, 2 chronic HBsAg carriers with no clinical symptoms) were prepared using interspecific in vitro fertilization between zona-free golden hamster ova and human spermatozoa, and the frequencies of aberration spermatozoa were compared between subjects of HBV infection and controls. Fluorescence in situ hybridization (FISH) to sperm chromosome spreads was carried out with biotin-labeled full length HBV DNA probe to detect the specific HBV DNA sequences in the sperm chromosomes. The total frequency of sperm chromosome aberrations in HBV infection group (14.8 %, 33/223) was significantly higher than that in the control group (4.3 %, 5/116). Moreover, the sperm chromosomes in HBV infection patients commonly presented stickiness, clumping, failure to staining, etc, which would affect the analysis of sperm chromosomes. Specific fluorescent signal spots for HBV DNA were seen in sperm chromosomes of one patient with chronic persistent hepatitis. In 9 (9/42) sperm chromosome complements containing fluorescent signal spots, one presented 5 obvious FISH spots, others presented 2 to 4 signals. There was significant difference of fluorescence intensity among the signal spots. The distribution of signal sites among chromosomes was random. HBV infection can bring about mutagenic effects on sperm chromosomes. Integrations of viral DNA into sperm chromosomes which are multisites and nonspecific, can further increase the instability of sperm chromosomes. This study suggested that HBV infection can create extensively hereditary effects by alteration genetic constituent and/or induction chromosome aberrations, as well as the possibility of vertical transmission of HBV via the germ line to the next generation.

Radiation- and chemical-induced structural chromosome aberrations in human spermatozoa

Previous studies on the clastogenic effects of mutagens on human sperm chromosomes were reviewed. A marked increase of structural chromosome aberrations (SCAs) has been reported in the spermatozoa irradiated in vitro with five kinds of ionizing radiation ( 137 Cs γ-, 60 Co γ-, X-, and 3 H β-rays and 252 Cf neutrons). The micronucleus (MN) test with hybrid two-cell embryos generated from human sperm and hamster oocytes was shown to be useful as a simple and rapid method for assessing the effects of radiation. Radiosensitivity of human spermatozoa was highest, being followed by golden hamster, Chinese hamster and mouse spermatozoa. Chromosome-damaging effects were also found with some chemicals (bleomycin, daunomycin, methyl methanesulfonate, triethylenemelamine, neocarzinostatin, N-methyl- N′-nitro- N-nitorosoguanidine and mitomycin C (MMC)), but not with other chemicals (urethane, nitrobenzene, dioxin, cyclophosphamide (CP), benzo(a)pyrene (BP) and N-nitrosodimethylamine (NDMA)). The clastogenicity of chemical metabolites was confirmed for CP and BP, by using the S9-based metabolic activation system. The results of sperm chromosome analysis from cancer patients who had undergone radio- and/or chemotherapy were contradictory among investigators and further studies are necessary. The importance of mutagenicity testing with human spermatozoa is discussed.

In vitro spontaneous parthenogenetic activation of golden hamster oocytes

Parthenogenetic activation is a major hurdle to be cleared for the examination of the human sperm chromosome after intracytoplasmic injection (ICSI) into golden hamster oocytes. Various factors that affect spontaneous activation of hamster oocytes were, therefore, investigated in this study. We collected cumulus–oocyte complexes (COC) from the oviducts of superovulated females and washed them thoroughly with Ca 2+-containing or Ca 2+-free TALP-HEPES medium (handling media). We cultured oocytes with intact cumulus or those without cumulus (removed by previous hyaluronidase treatment) in Ca 2+-containing or -free m-TALP-3 for 6 or 12 h before examining for their activation. Among the oocytes recovered 17 h post-hCG, 92–94% were parthenogenetically activated by 6 h of in vitro culture. Activation rate in the oocytes collected at 13.5 h post-hCG (53%) was significantly ( P<0.05) lower than that in the oocytes collected 17 h post-hCG (92%), indicating that the spontaneous activation rate increased as the oocytes became older. Both cumulus-intact and cumulus-free oocytes had similar ( P>0.05) activation rates when cultured in vitro, suggesting that hyaluronidase treatment had no effect on the rate of oocyte activation. Omission of Ca 2+ from the handling medium also had no effect on the activation of the oocytes. The rate of spontaneous activation of the oocytes cultured in calcium-free medium for 6 (9%) and 12 h (16%) was significantly ( P<0.01) lower than that (94%) of the control oocytes cultured in Ca 2+-containing medium, implying a positive influence of Ca 2+ on in vitro activation of hamster oocytes. When we cultured the oocytes first in calcium-free medium for 6 h, and then in calcium-containing medium for 6 h, 94% were activated, which is comparable to the rate for oocytes continuously cultured in Ca 2+-containing medium. This indicates that the inhibition of hamster oocyte activation in Ca 2+-free medium is reversible and can be used to control spontaneous activation of golden hamster oocytes.

Effect of paternal age on human sperm chromosomes

Objective: To investigate whether increased age alters the frequency and type of chromosomal anomalies in human spermatozoa. Design: Semen specimens were collected from donors via masturbation; cytogenetic studies were performed on sperm chromosomes after heterologous (human-hamster) in vitro fertilization. Setting: Cytogenetics Laboratory, Genetics Department, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Brazil. Patients(s): Seven men ages 59–74 (older group) and five men ages 23–39 (control group). Main Outcome Measure(s): Frequency and types of chromosomal anomalies in older and control group donors. Result(s): The frequency of numerical and structural aberrations (acentric fragments and complex radial figures) was significantly greater in chromosomes of older donors when compared with those of the control group. Conclusion(s): The higher frequency of sperm chromosome aberrations in older men was mainly a result of increased nondisjunction, acentric fragments, and complex radial figures.

Intracytoplasmic sperm injection could minimize the incidence of prematurely condensed human sperm chromosomes

Objective: To compare the fertilization and prematurely condensed human sperm chromosomes (PCCs) rates between two intracytoplasmic sperm injection (ICSI) techniques. Design: A retrospective study. Setting: The data were obtained from the University of British Columbia in vitro fertilization (IVF) laboratory. Patient(s): ICSI cycles (n = 105) were performed for couples suffering from severe male-factor infertility and dysfunction of fertilization. Intervention(s): Two types of ICSI techniques were used for ICSI procedures. Main Outcome Measure(s): Fertilization and pregnancy rates in group B using the improved ICSI technique were compared with those of group A using the standard ICSI technique. Unfertilized oocytes from the two groups were studied with cytogenetic methods. Result(s): Oocyte damage dropped from 14.8% in group A to 5.3% in group B. Normal fertilization for each group was 57.3% and 88.4%, respectively ( P<.05). Pregnancy rate per egg retrieval was 15.6% in group A and 27.4% in group B ( P<.05). PCCs occurred in 19.4% of unfertilized oocytes in group A and did not occur in group B. Conclusion(s): This study indicates that ICSI not only yields high fertilization rates, but also minimizes the incidence of PCCs. It may be directly related to two crucial steps (immobilization of sperm and aspiration of oocyte cytoplasm) used in ICSI procedures. This study also suggests that it is possible to overcome one cause of IVF failure resulting from the formation of PCCs by using the improved ICSI technique.

Chromosome analysis of human spermatozoa following in vitro exposure to cyclophosphamide, benzo(a)pyrene and N-nitrosodimethylamine in the presence of rat liver S9

For the purpose of assessing mutagenic effects (clastogenicity) of metabolites derived from chemical mutagens/carcinogens on human sperm chromosomes, spermatozoa were exposed in vitro to cyclophosphamide (CP), benzo(a)pyrene (BP) or N-nitrosodimethylamine (NDMA) for 2 h in the presence or absence of rat liver S9, a metabolic activator of these chemicals. After in vitro fertilization between human spermatozoa and zona-free hamster oocytes, chromosome complements of sperm origin were analyzed cytogenetically. In the absence of S9, none of three chemicals (20 μg/ml CP, 200 μg/ml BP and 20 mg/ml NDMA) caused a significant increase in spermatozoa with structural chromosome aberrations (8.6, 10.0 and 7.5%), as compared with their matched controls (10.9, 11.0 and 8.5%). In the presence of S9, however, a significant increase in chromosomally abnormal spermatozoa was observed in CP (37.1%, P<0.001) and BP (31.0%, P<0.001), indicating that enzymatic activation of CP and BP induced chromosomal abnormalities in human sperm. In contrast, NDMA did not induce chromosome aberrations in human spermatozoa by S9 treatment, although positive results have been observed in somatic cells. The present results on in vitro clastogenicity of CP, BP and NDMA are consistent with the results in previous in vivo studies with murine spermatozoa. Our S9/human sperm chromosome assay seems to be useful for estimation of hereditary risk of chemicals in human. Because most chemicals need metabolic activation to bind to DNA.

Non-random chromosome positioning in human sperm and sex chromosome anomalies following intracytoplasmic sperm injection

Chromosome paint for chromosome 18 hy b ridised in more than 80% (190/234) of sperm examined, and chromosome paint for X chromosome hy b ridised in just over 40% ( 2 3 0 / 5 5 3 ) . The sperm tail was used as a reference to identify apical or basal position. Chromosome 18 was found near the s p e rm tail in almost 60% of the sperm (113/190), while the X chromosome was found near the sperm tail in less than 40% ( 8 8 / 2 3 0 ) . This shows that chromosome 18 is preferentially l o c ated in the basal region of the sperm nucleus, while the X chromosome is preferentially located in the apical regi o n . The placement of chromosomes within the sperm nucleus m ay have implications for assisted reproductive technologi e s ( A RT ) , and may help explain the apparent increase in sexchromosome aberr ations in ICSI offspri n g . This increase could be due to the fact that the X chromosome in sperm nuclei preferentially localises in the apical regi o n .I n such n u c l e i , the S-phase of the cell cycle may be delayed due to the decreased rate of nuclear decondensation in the apical regi o n of the sperm head, h i n d e ring progression to the onset of firs t mitosis in the zygote. This may lead to mitotic err o rs in the d i s t ri bution of the X chromosome during first cleava g e , implying that such positioning of the sex chromosome could lead to the increase in sex-chromosome anomalies follow i n g I C S I . All animal procedures were approved by the ORPRC Institutional A n i m a l Care and Use Committee. Human sperm were obtained from the Fo l l a s L a b o r at o ries after Institutional Review Board approva l .This research wa s sponsored by grants to GS by the NIH.

Human sperm chromosome complements in chemotherapy patients and infertile men.

Our studies of human sperm karyotypes and interphase sperm analyzed by fluorescence in situ hybridization (FISH) have both yielded estimates of disomy frequencies of approximately 0.1% per chromosome with an overall aneuploidy frequency in human sperm of approximately 5%-6%. However, the distribution of aneuploidy in sperm is not even, as our data from sperm karyotypes and multicolour FISH analyses both demonstrate a significant increase in the frequency of aneuploidy for chromosome 21 and the sex chromosomes. We have studied men at increased risk of sperm chromosomal abnormalities including cancer patients and infertility patients. Testicular cancer patients were studied before and 2-13 years after chemotherapy (CT) with BEP (bleomycin, etoposide, cisplatin). Sperm karyotype analysis on 788 sperm demonstrated no significant difference in the frequency of numerical or structural chromosomal abnormalities post-CT vs pre-CT. Similarly, multicolour FISH analysis for chromosomes 1, 12, XX, YY and XY in 161,097 sperm did not detect any significant differences in the frequencies of disomy before and after treatment. However, recent evidence has suggested a significant increase in the frequency of disomy and diploidy during CT. We have found that infertile men, who would be candidates for intracytoplasmic sperm injection, have an increased frequency of chromosomally abnormal sperm karyotypes. Also, FISH analysis for chromosomes 1, 12, 13, 21, XX, YY and XY in 255,613 sperm demonstrated a significant increase in chromosomes 1, 13, 21, and XY disomy in infertile men compared with control donors.