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1.
Renée Martin 《Chromosoma》1998,107(6-7):523-527
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.
Received: 4 July 1998; in revised form: 7 September 1998 / Accepted: 8 September 1998 相似文献
2.
E. G. Gordeeva L. V. Shileiko O. S. Pankratova L. F. Kurilo 《Russian Journal of Genetics》2011,47(6):732-738
Analysis of sperm aneuploidy in 11 healthy men using two-or three-color FISH permitted to determine the average frequency
of disomy for chromosomes 13 and 21 (0.11% and 0.2%, respectively), disomy for chromosome 18 (0.05%) and to reveal gonosomal
aneuploidy variants and their frequency. The frequency of XX disomy was 0.04%; XY, 0.17%; YY, 0.06%; and gonosomal nullisomy,
0.29%. We assessed the frequency of meiotic nondisjunction of 13, 21, 18, X, and Y chromosomes and the frequency of XX, XY,
and YY diploid spermatozoa. The XY variant prevailed in gonosomal aneuploidy and diploidy and was associated with abnormal
chromosomal segregation in meiotic anaphase I. The contribution of human sperm chromosomal imbalance to early embryonic lethality
and to some forms of chromosomal abnormalities in the off-spring is discussed. 相似文献
3.
Alain Ducos Hélène-Marie Berland Nathalie Bonnet Anne Calgaro Sébastien Billoux Nicolas Mary Amélie Garnier-Bonnet Roland Darré Alain Pinton 《遗传、选种与进化》2007,39(5):583-597
The chromosomal control of pig populations has been widely developed in France over the last ten years. By December 31st, 2006, 13 765 individuals had been karyotyped in our laboratory, 62% of these since 2002. Ninety percent were young purebred boars controlled before service in artificial insemination centres, and 3% were hypoprolific boars. So far, 102 constitutional structural chromosomal rearrangements (67 since 2002) have been described. Fifty-six were reciprocal translocations and 8 peri- or paracentric inversions. For the first time since the beginning of the programme and after more than 11 000 pigs had been karyotyped, one Robertsonian translocation was identified in 2005 and two others in 2006. The estimated prevalence of balanced structural chromosomal rearrangements in a sample of more than 7700 young boars controlled before service was 0.47%. Twenty-one of the 67 rearrangements described since 2002 were identified in hypoprolific boars. All were reciprocal translocations. Twelve mosaics (XX/XY in 11 individuals, XY/XXY in one individual) were also diagnosed. Two corresponded to hypoprolific boars, and three to intersexed animals. The results presented in this communication would justify an intensification of the chromosomal control of French and, on a broader scale, European and North-American pig populations. 相似文献
4.
Pauciullo A Nicodemo D Peretti V Marino G Iannuzzi A Cosenza G Di Meo GP Ramunno L Iannuzzi L Rubes J Di Berardino D 《Theriogenology》2012,78(3):688-695
The present study reports on the frequency of X-Y aneuploidy in the sperm population of two minor cattle breeds reared in Italy, namely Modicana and Agerolese, which are listed in the "Anagraphic Register of autochthonous cattle populations with limited distribution". More than 50 000 sperm nuclei from 11 subjects (5 and 6, respectively for each breed) have been analyzed by the fluorescent in situ hybridization with the Xcen and Y-chromosome specific painting probes. The fraction of X- and Y-bearing sperm was close to the 1:1 ratio in the Modicana breed, whereas in the Agerolese the Y-fraction was significantly higher (P < 0.002) compared to the X-counterpart. The mean rates of X-Y aneuploidy were 0.510 and 0.466%, respectively, in the two breeds; no significant differences were found among individual bulls within each breed. Average frequencies of disomic and diploid sperm were 0.425 and 0.085% in the former and 0.380 and 0.086% in the latter. In both breeds, (a) disomy was significantly more frequent than diploidy (P < 0.01), (b) YY disomy was significantly (P < 0.001) more frequent than XY or XX; (c) MI errors (XY disomy) were significantly (P < 0.01) less represented than MII (XX + YY disomy). Compared to the dairy (Italian Friesian and Brown) and meat (Podolian and Maremmana) breeds previously analyzed, the "minor" breeds investigated in the present study showed a significantly (P < 0.002) higher rate of X-Y aneuploidy (0.486 vs. 0.159 and 0.190%, respectively). Considering all the breeds analyzed -so far- and assuming no significant interchromosomal effect, the baseline level of aneuploidy in the sperm population of the species Bos taurus was estimated as 5.19%. Establishing the baseline level of aneuploidy in the sperm population of the various livestock species/breeds engaged in animal production could reveal useful for monitoring future trends of their reproductive health, especially in relation to management errors and/or environmental hazards. 相似文献
5.
Males with a 47,XYY karyotype generally have chromosomally normal children, despite the high theoretical risk of aneuploidy. Studies of sperm karyotypes or FISH analysis of sperm have demonstrated that the majority of sperm are chromosomally normal in 47,XYY men. There have been a number of meiotic studies of XYY males attempting to determine whether the additional Y chromosome is eliminated during spermatogenesis, with conflicting results regarding the pairing of the sex chromosomes and the presence of an additional Y. We analyzed recombination in the pseudoautosomal region of the XY bivalent to determine whether this is perturbed in a 47,XYY male. A recombination frequency similar to normal 46,XY men would indicate normal pairing within the XY bivalent, whereas a significantly altered frequency would suggest other types of pairing such as a YY bivalent or an XYY trivalent. Two DNA markers, STS/STS pseudogene and DXYS15, were typed in sperm from a heterozygous 47,XYY male. Individual sperm (23,X or Y) were isolated into PCR tubes using a FACStarPlus flow cytometer. Hemi-nested PCR analysis of the two DNA markers was performed to determine the frequency of recombination. A total of 108 sperm was typed with a 38% recombination frequency between the two DNA markers. This is very similar to the frequency of 38.3% that we have observed in 329 sperm from a normal 46,XY male. Thus our results suggest that XY pairing and recombination occur normally in this 47,XYY male. This could occur by the production of an XY bivalent and Y univalent (which is then lost in most cells) or by loss of the additional Y chromosome in some primitive germ cells or spermatogonia and a proliferative advantage of the normal XY cells. 相似文献
6.
Estimates of sperm sex chromosome disomy and diploidy rates in a 47,XXY/46,XY mosaic Klinefelter patient 总被引:6,自引:0,他引:6
A 47,XXY/46,XY male was investigated for the incidence of aneuploidy in sperm sex chromosomes using a three-colour X/Y/18
fluorescence in situ hybridisation (FISH) protocol. A total of 1701 sperm nuclei were analysed. The ratio of X-bearing to
Y-bearing sperm did not differ from the expected 1 : 1 ratio although there were more 23,Y sperm than 23,X sperm (844 vs 795).
There was a significantly increased proportion of disomy XY and XX sperm compared with normal controls (0.41% vs 0.10%, P < 0.001 and 0.29% vs 0.04%, P < 0.01). However, the incidence of YY sperm was similar to the controls (0.06% vs 0.02%). The diploidy rate was also significantly
increased (1.7% vs 0.13%, P < 0.0001), as was disomy 18 (0.71% vs 0.01%) and 25,XXY (0.47% vs 0%). The results support the hypothesis that some 47,XXY
cells are able to undergo meiosis and produce mature spermatozoa. Patients with mosaic Klinefelter syndrome with severe oligozoospermia
have significantly elevated incidences of disomy XY and XX sperm and may be at a slightly increased risk of producing 47,XXX
and 47,XXY offspring. Additionally, they may be at risk of producing offspring with autosomal trisomies. Hence, patients with
Klinefelter mosaicism scheduled for intracytoplasmic sperm injection intervention should first undergo FISH analysis of their
sperm to determine their risk.
Received: 16 November 1998 / Accepted: 16 February 1999 相似文献
7.
C. A. Moreira-Filho Priscila G. Otto Z. Mustacchi O. Frota-Pessoa P. A. Otto 《Human genetics》1980,55(3):309-314
Summary Cells from an XX true hermaphrodite expressed a reduced amount of H-Y antigen when compared with normal XY cells and with cells from his father, who had an XY/XX chromosomal constitution. His mother had a normal karyotype and was H-Y negative. The four brothers of the patient were clinically and karyotypically normal. An X-Y interchange followed by random inactivation of the X chromosome is proposed to explain the H-Y antigen titer found in the patient. 相似文献
8.
We report a successful second delivery of a healthy infant fathered using refrozen thawed testicular sperm from an infertile male chimera. We also examined sex chromosome distribution of the seminiferous tubule. Intracytoplasmic sperm injection (ICSI) was performed using the remaining refrozen testicular sperm, which had been stored during the first treatment. Biopsied testicular cells were examined by fluorescence in situ hybridization (FISH) and the peripheral lymphocyte karyotype was tested using a G-band. Following ICSI, a second pregnancy was established, and a healthy girl was successfully delivered at 40 gestational weeks without complications. Although the husband’s lymphocyte chromosomal analysis revealed a 46, XX [28]/46, XY [2] karyotype, the seminiferous tubule cells on histological examination by FISH were chimeric sex chromosome type XX [18]/XY [82]. In conclusion, this is a very rare case report of a successful subsequent delivery of a healthy infant (46, XX) from an infertile true hermaphrodite (46, XX/46, XY) using refrozen thawed testicular sperm. The seminiferous tubule cells’ karyotype ratio differed from that of the lymphocytes. 相似文献
9.
Aneuploid spermatozoa in infertile men: teratozoospermia. 总被引:7,自引:0,他引:7
Cristina Templado Tina Hoang Calvin Greene Alfred Rademaker Judy Chernos Renée Martin 《Molecular reproduction and development》2002,61(2):200-204
We and others have demonstrated that infertile men who are candidates for intracytoplasmic sperm injection (ICSI) have an increased frequency of chromosomal abnormalities in their sperm. Reports based on prenatal diagnosis of ICSI pregnancies have confirmed the increased frequency of chromosomal abnormalities in offspring. Most studies to date have lumped various types of infertility together. However, it is quite likely that some subsets of infertility have an increased risk of sperm chromosomal abnormalities whereas others do not. We have studied nine men with severe teratozoospermia (WHO, 1992 criteria, 0-13% morphologically normal forms) by multicolour fluorescence in situ hybridisation (FISH) analysis to determine if they have an increased frequency of disomy for chromosomes 13, 21, XX, YY, and XY, as well as diploidy. All of the men also had aesthenozoospermia (< 50% forward progression) but none of the men had oligozoospermia (<20 x 10(6) sperm/ml). The patients ranged in age from 20 to 49 years (mean 33.2 years) in comparison to 18 normal control donors who were 23 to 58 years (mean 35.6 years). The control donors had normal semen parameters and no history of infertility. A total of 180,566 sperm were scored in the teratozoospermic men with a minimum of 10,000 sperm analyzed/donor/chromosome probe. There was a significant increase in the frequency of disomy in teratozoospermic men compared to controls for chromosomes 13 (.23 vs.13%), XX (.13 vs.05%), and XY (.50 vs.30%) (P <.0001, 2-tailed Z statistic). This study indicates that men with teratozoospermia and aesthenozoospermia but with normal concentrations of sperm have a significantly increased frequency of sperm chromosomal abnormalities. 相似文献
10.
Pinton A Barasc H Raymond Letron I Bordedebat M Mary N Massip K Bonnet N Calgaro A Dudez AM Feve K Riquet J Yerle M Ducos A 《Cytogenetic and genome research》2011,133(2-4):202-208
Klinefelter's syndrome (KS) is the most common sex chromosome abnormality identified in human males. This syndrome is generally associated with infertility. Men with KS may have a 47,XXY or a 46,XY/47,XXY karyotype. Studies carried out in humans and mice suggest that only XY cells are able to enter and complete meiosis. These cells could originate from the XY cells present in mosaic patients or from XXY cells that have lost one X chromosome. In pig, only 3 cases of pure 39,XXY have been reported until now, and no meiotic analysis was carried out. For the first time in pig species we report the analysis of a 38,XY/39,XXY boar and describe the origin of the supplementary X chromosome and the chromosomal constitutions of the germ and Sertoli cells. 相似文献
11.
J. P. Siffroi 《Andrologie》2001,11(1):9-14
Klinefelter’s syndrome is a common sex chromosomal aberration generally characterized by hypergonadotrophic hypogonadism and azoospermia. However, spermatogenesis impairment is variable and severe oligozoospermia can be found in some men, particularly those exhibiting a mosaic karyotype 47,XXY/ 46,XY. New reproductive technologies, such as intracytoplasmic sperm injection (ICSI), allow Klinefelter patients to have a progeny, even those who are azoospermic after testicular sperm recovery. The question therefore arises of whether or not there is a genetic risk for pregnancies from affected fathers. Sperm karyotyping, by in vitro penetration of zona-free hamster eggs or by fluorescence in-situ hybridization (FISH), is a method of choice for measuring aneuploidy rate in spermatozoa of patients carrying gonosomal abnormalities. A theoretical model would predict a high level of 24,XX and/or 24,XY disomic sperm cells in Klinefelter patients if 47,XXY spermatogonia were able to complete meiosis and achieve spermatogenesis. Interestingly, current observations show that the rate of abnormal spermatozoa in these patients is low, around 1–2%, which indicates that only 46,XY spermatogonia can produce mature sperm cells and that oligozoospermic Klinefelter patients probably carry a 47,XXY / 46,XY mosaicism, at least at the testicular level. However, this low but statistically significant level of disomic spermatozoa emphasizes the fact that their spermatogenesis occurs in a compromised environment which could increase the risk of meiotic errors. Therefore, the possible occurrence of autosomal aneuploidies in children born from Klinefelter fathers leads to the following recommendations: a) individual analysis by FISH of the sperm aneuploidy rate in each Klinefelter patient candidate for ICSI; b) proposal of fetal karyotyping after amniocentesis in pregnancies obtained by this technique. 相似文献
12.
Meiotic segregation of the sex chromosomes was analysed in sperm nuclei from a man with Klinefelter’s karyotype by three-colour
FISH. The X- and Y-specific DNA probes were co-hybridized with a probe specific for chromosome 1, thus allowing diploid and
hyperhaploid spermatozoa to be distinguished. A total of 2206 sperm nuclei was examined; 958 cells contained an X chromosome,
1077 a Y chromosome. The ratio of X : Y bearing sperm differed significantly from the expected 1 : 1 ratio (χ2 = 6.96; 0.001 < P < 0.01). Sex-chromosomal hyperhaploidy was detected in 2.67% of the cells (1.22% XX, 1.36% XY, 0.09% YY) and a diploid constitution
in 0.23%. Although the frequency of 24,YY sperm was similar to that detected in fertile males, the frequencies of 24,XX,
24,XY and diploid cells were significantly increased. A sex-chromosomal signal was missing in 4.26% of the spermatozoa. This
percentage appeared to be too high to be attributed merely to nullisomy for the sex chromosomes and was considered, at least
partially, to be the result of superposition of sex-chromosomal hybridization signals by autosomal signals in a number of
sperm nuclei. The results contribute additional evidence that 47,XXY cells are able to complete meiosis and produce mature
sperm nuclei.
Received: 6 November 1996 相似文献
13.
Chromosomal imbalance in gametes and embryos is one of the factors contributing to early embryonic mortality. Although the rate of chromosomally abnormal sperm cells is low and usually does not exceed 1%, there is no clear indication of fertilizing potential of such gametes. The aim of the experiment was to investigate the type and incidence of numerical chromosomal aberrations in spermatozoa produced by fertile boars used in artificial insemination (AI). We used the protocol of fluorescent in situ hybridization (FISH) on sperm interphase nuclei with molecular probes for porcine chromosome pairs 1 and 10. Altogether 12?348 sperm cells were examined. Disomy was observed in spermatozoa of all seven AI boars whereas only one diploid cell was identified in all screened sperm cells. The average rate of chromosomally unbalanced sperm was 0.105% (13/12 348) with an inter-individual variation from 0.048% to 0.194%. Among abnormal sperm cells, both disomy (0.097%) and diploidy (0.008%) were detected. Nullisomy was not included into calculations. The estimated aneuploidy rate calculated by doubling the number of disomic cells was 0.194%. Chromosome pair 10 was significantly more often involved in non-disjunction (75%, 9/12 aneuploid sperm cells) than chromosome pair 1 (25%, 3/12). We have shown for the pig that the rate of disomic cells falls into a range presented by other authors, whereas that of diploid spermatozoa appeared to be lower in the present study. In conclusion, numerical chromosome aberrations were present in spermatozoa of all AI boars analyzed in this study. Therefore, it can be assumed that the presence of unbalanced spermatozoa at the level observed in fertile males does not significantly affect their reproductive potential. 相似文献
14.
Chromosomes of human sperm: Variability among normal individuals 总被引:13,自引:5,他引:8
B. Brandriff L. Gordon L. Ashworth G. Watchmaker D. Moore II A. J. Wyrobek A. V. Carrano 《Human genetics》1985,70(1):18-24
Summary The chromosomal constitution of 2468 human sperm cells been investigated by fusion of human sperm with hamster eggs. The overall frequency of cells with structural aberrations was 7.7%, ranging from 1.9% to 15.8%, and varying significantly among individuals. The highest frequency occurred in sperm from the oldest donor (49 years), who also had had a vasectomy reversal three years prior to sampling. The overall aneuploidy frequency was 1.7%, ranging from 0.6% to 3.1%. In nine out of ten donors from whom blood samples were available the frequency of sperm cells with structural aberrations was higher than that for lymphocytes. Two previously reported donors (Brandriff et al. 1984) were resampled after an interval of 14 and 16 months respectively, and were each found to have similar frequencies of sperm chromosome abnormalities at both sampling times. A father-son pair included in the study had several chromosome breakpoints in common, although no more frequently than unrelated individuals. 相似文献
15.
To examine interindividual differences in sperm chromosome aneuploidy, repeated semen specimens were obtained from a group of ten healthy men, aged 20-21 at the start of the study, and analyzed by multi-color fluorescence in situ hybridization (FISH) analysis to determine the frequencies of sperm aneuploidy for chromosomes X, Y, 8, 18 and 21 and of diploidy. Semen samples were obtained three times over a five-year period. Statistical analysis examining the stability of sperm aneuploidy over time by type and chromosome identified two men who consistently exhibited elevated frequencies of sperm aneuploidy (stable variants): one with elevated disomy 18 and one with elevated MII diploidy. Differences among frequencies of aneuploidy by chromosome were also seen. Overall, disomy frequencies were lower for chromosome X, 8 and 18 than for chromosomes 21 or Y and for XY aneuploidy. The frequency of chromosome Y disomy did not differ from XY sperm frequency. Also, the frequency of meiosis I (XY) and II (YY + XX) sex chromosome errors did not differ in haploid sperm, but the frequency of MII errors was lower than MI errors in diploid sperm. Frequencies of sperm aneuploidy were similar between the first sampling period and the second, two years later. However, the frequency of some types of aneuploidy (XY, disomy Y, disomy 8, total autosomal disomies, total diploidy, and subcategories of diploidy) increased significantly between the first sampling period and the last, five years later, while others remained unchanged (disomy X, 21 and 18). These findings confirm inter-chromosome differences in the frequencies of disomy and suggest that some apparently healthy men exhibit consistently elevated frequencies of specific sperm aneuplodies. Furthermore, time/age-related changes in sperm aneuploidy may be detected over as short a period as five years in a repeated-measures study. 相似文献
16.
Analysis of sex chromosome aneuploidy in sperm from fathers of Turner syndrome patients 总被引:8,自引:0,他引:8
O. Martínez-Pasarell Carme Nogués Mercè Bosch Josep Egozcue Cristina Templado 《Human genetics》1999,104(4):345-349
Numerical sex chromosome abnormalities were analyzed in sperm from four fathers of Turner syndrome patients of paternal origin
to determine whether there was an increased frequency of sex chromosome aneuploidy and to elucidate whether meiotic malsegregation
mechanisms could be involved in the origin of Turner syndrome. Determination of the parental origin of the single X chromosome
(maternal in all four cases) and exclusion of X and Y mosaicism were carried out by polymerase chain reaction amplification
of five X chromosome polymorphisms and three Y chromosome segments. A total of 45,299 sperm nuclei from Turner fathers and
85,423 sperm nuclei from eight control donors was analyzed by three-color fluorescence in situ hybridization. The four patients
showed a significant increase in the percentages of XY sperm (mean 0.22%; range 0.20% to 0.22%) compared with control donors
(mean 0.11%; range 0.06% to 0.18%). These results suggest that the four individuals have an increased frequency of nondisjunctional
errors in meiosis I, resulting in the production of an increased proportion of XY spermatozoa and of sperm lacking a sex chromosome.
Received: 24 November 1998 / Accepted: 2 February 1999 相似文献
17.
Rate division of human lymphocytes was studied in 85 healthy siblings and 142 normal non-related individuals using sister chromatid differential staining in standard conditions of cell culturing. It was shown that proliferation of male lymphocytes exceeds that of female cells. This sexual dimorphism does not depend on the time of fixation of cell cultures and probably is conditioned by differential chromosomal constitution of the two sexes. The study of sex chromosome mosaics revealed rate modification of cell proliferation in the line: 45,X greater than 46,XY greater than 46,XX. The possibility of influence of heterochromatin and sex chromosomal genes on control of cell division is discussed. 相似文献
18.
Five true hermaphrodite pigs and two male pseudohermaphrodite pigs were studied. A 38XX sex chromosome constitution was found in peripheral leucocytes of three true hermaphrodites and in one male pseudohermaphrodite; XX/XY mixoploidy was present in the leucocytes of the remaining male pseudohermaphrodite. The occurrence of C19 steroids, including 16-androstenes, in the testicular tissue and submaxillary gland of intersex pigs was of a similar pattern to that found previously in mature boars, and masculinization of the genital tract was related to the amount of testicular tissue present. It is postulated that in the absence of germ cells in the testicular tissue of intersex pigs the Sertoli cells may be involved in the metabolism of dehydroepiandrosterone to 5-androstenediol, a possible testosterone precursor in the pig. The high levels of 16-androstenes found in the submaxillary gland of intersex pigs indicates that these steroids are responsible for 'boar taint' in these animals. In contrast to the boar, no consistent relationship was found between the occurrence of C19 steroids and the degree of masculinization of the submaxillary gland; it is postulated that the predominantly female genetic constitution may have affected the response of the salivary gland to androgen. 相似文献
19.
Increased incidence of hyperhaploid 24,XY spermatozoa detected by three-colour FISH in a 46,XY/47,XXY male 总被引:11,自引:0,他引:11
Edith Chevret Sophie Rousseaux Michèle Monteil Yves Usson Jean Cozzi Roberte Pelletier Bernard Sèle 《Human genetics》1996,97(2):171-175
Meiotic segregation of gonosomes from a 46,XY/47,XXY male was analysed by a three-colour fluorescence in situ hybridisation (FISH) procedure. This method allows the identification of hyperhaploid spermatozoa (with 24 chromosomes), diploid spermatozoa (with 46 chromosomes) and their meiotic origin (meiosis I or 11). Alpha satellite DNA probes specific for chromosomes X, Y and 1 were observed on 27,097 sperm nuclei. The proportions of X-and Y -bearing sperm were estimated to 52.78% and 43.88%, respectively. Disomy (24,XX, 24,YY, 24,X or Y,+1) and diploidy (46,XX, 46,YY, 46,XY) frequencies were close to those obtained from control sperm, whereas the frequency of hyperhaploid 24,XY spermatozoa (2.09%) was significantly increased compared with controls (0.36%). These results support the hypothesis that a few 47,XXY germ cells would be able to complete meiosis and to produce mature spermatozoa. 相似文献
20.
In order to ascertain whether or not sister-chromatid exchange (SCE) differs in relation to sex, SCE rates in XX and XY cells from 10 specimens of marmoset (Callithrix jacchus) were examined. The choice of this primate is particularly suitable for three reasons: most individuals have a chimeric constitution, the X chromosome is quite large and the Y chromosome is particularly small. Therefore, the influence of possible differences in their exposure to the external environment can be eliminated. The results obtained did not reveal any significant difference between SCE rates in male and female cells in any of the examined individuals. 相似文献