Objective:Due to the extensive use of intracytoplasmic sperm injection (ICSI) in assisted reproduction, not only among couples with severe male factor infertility problems, but to a broader scale, a lot of concern has been raised regarding the safety of the method and its implications in epigenic control and imprinting dysregulation. This review means to provide a comprehensive report of the published scientific data, outline putative associations between ICSI and epigenetic control,and suggest measures to improve the current state of affairs and reach more scientifically consolidated results.
Methods:This review was conducted by studying a broad spectrum of articles dealing with the subject of epigenetic control and its relation with ICSI. We tried to view the two subjects as parallel procedures that occur in the organism and by delineating the molecular and biochemical steps that comprise them make suggestions about putative associations between ICSI and epigenetic control.
Conclusions:No hard evidence presented at the moment can prove or disapprove ICSI's implications in epigenetic control. Nevertheless, we take the view that more comprehensive, long-term, and properly designed studies are imperative to be applied on a large-scale basis. We urge cautiousness, since the welfare of our progeny is what is at stake.
1. Palermo G, Joris H, Devroey P, Van Steirteghem AC. Pregnancies after intracytoplasmic injection of single spermatozoon into an oocyte. Lancet1992;340:17-18.
2.
2. Lahteen Maki A, Reima I, Hovatta O. Treatment of severe male immunological infertility by intracytoplasmic sperm injection. Hum Reprod1995;10:2824-2828.
3.
3. Nagy P, Verheyen G, Liu J, et al. Results of 55 intracytoplasmic sperm injection cycles in the treatment of male-immunological infertility. Hum Reprod1995;10:1775-1780.
4.
4. Nikolettos N, Al-Hasani S, Baukloh V, et al. The outcome of intracytoplasmic sperm injection in patients with retrograde ejaculation. Hum Reprod1999;14:2229-2296.
5.
5. Chung PH, Palermo G, Schlegel PN, Veeck LL, Bid JF, Rosenwaks Z. The use of intracytoplasmic sperm injection with ejaculates from anejaculatory men. Hum Reprod1998;13:1854-1858.
6.
6. Benadiva CA, Nulsen J, Stano L, Jennings J, Givargis HB, Maier D. Intracytoplasmic sperm injection overcomes previous fertilisation failure with conventional in vitro fertilisation. Fertil Steril1999;72:1041-1044.
7.
7. Schatte EC, Orejuela FJ, Lipshultz LI, Kim ED, Lamb DJ. Treatment of infertility due to anejaculation in the male with electroejaculation and intracytoplasmic sperm injection. J Urol2000;163:1717-1720.
8.
8. Visconn PE, Kopf GS. Regulation of protein phosphorylation during sperm capacitation. Biol Reprod1998;59:1-6.
9.
9. Ho HC, Suarez SS. Hyperactivation of mammalian spermatozoa: Function and regulation. Reproduction2001;122:519-526.
10.
10. Liu J, Yu S, Litman D, et al. Identification of a methylation imprint mark within the mouse Gnas locus. Mol Cell Biol2000;20:5808-5817.
11.
11. Perez C, Tilly J. Cumulus cells are required for an increased apoptotic potential in oocytes of aged mice. Hum Reprod1997;12:2781-2783.
12.
12. Van Blerkom J, Davis PW. DNA strand breaks and phosphatidylserine redistribution in newly ovulated and cultured mouse and human oocytes: Occurrence and relationship to apoptosis. Hum Reprod1998;13:1317-1324.
13.
13. Barroso G, Morshedi M, Oehninger S. Analysis of DNA fragmentation, plasma membrane translocation of phosphatidylserine and oxidative stress in human spermatozoa. Hum Reprod2000;15:1338-1344.
14.
14. Huey S, Abuhamad A, Barrous G, et al. Perifollicular blood flow Doppler indices, but not follicular pO2, pCO2, or pH, predict oocyte developmental competence in in vitro fertilization. Fertil. Steril1999;72:707-712.
15.
15. Oehninger S, Gosden RG. Should ICSI be the treatment of choice for all cases of in-vitro conception? No, not in light of the scientific data. Hum Reprod2002;17:2237-2242.
16.
16. Orief Y, Dafopoulos K, Al-Hassani S. Should ICSI be used in non-male factor infertility?Reprod Biomed Online2004;9:348-356.
17.
17. Rycke M, Liebaers I, Van Steirteghem A. Epigenetic risks related to assisted reproductive technologies: Risk analysis and epigenetic inheritance. Hum Reprod2002;17:2487-2494.
18.
18. Thompson JG, Kind KL, Roberts CT, Robertson SA, Robinson JS. Epigenetic risks related to assisted reproductive technologies: Short- and long-term consequencies for the health of children conceived through assisted reproduction technology: More reason for caution?Hum Reprod2002;17:2783-2786.
19.
19. Ferguson-Smith AC, Surani MA. Imprinting and the epigenetic asymmetry between parental genomes. Science2001;293:1086-1089.
20.
20. Reik W, Walter J. Genomic imprinting: Parental influence on the genome. Nat Rev Genet2001;2:21-32.
21.
21. Morison IM, Reeve AE. A catalogue of imprinted genes and parent-of-origin effects in humans and animals. Hum Mol Genet1998;7:1599-1609.
22.
22. Tycko B, Morison IM. Physiological functions of imprinted genes. Cell Physiol2002;192:245-258.
23.
23. Walter J, Paulsen M. Imprinting and disease. Semin Cell Dev Biol2003;14:101-110.
24.
24. Weksberg R, Smith AC, Squire J, et al. Beckwith-Wiedemann syndrome demonstrates a role for epigenetic control of normal development. Hum Mol Genet2003;12:R61-R68.
25.
25. Bird A, Paulsen M. DNA methylation patterns and epigenetic memory. Genes Dev2002;16:6-21.
26.
26. Li E. Chromatin modification and epigenetic reprogramming in mammalian development. Nat Rev Genet2002;3:662-673.
27.
27. Liu J, Yu S, Litman D, et al. Identification of a methylation imprint mark within the mouse gnas locus. Mol Cell Biol2000;20:5808-5817.
28.
28. Medical Research Council (MRC) Mammalian Genetics Unit, Harwell. Mouse Imprinting. Available at: http://www.mgu.har.mrc.ac.uk/research/imprinting/.
29.
29. Moore T, Haig D. Genomic imprinting in mammalian development: A parental tug-of-war. Trends Genet1991;7:45-49.
30.
30. Haig D, Graham C. Genomic imprinting and the strange case of the insulin-like growth factor II receptor. Cell1991;64:1045-1046.
31.
31. Wilkins JF, Haig D. What good is genomic imprinting: The function of parent-specific gene expression. Nat Rev Genet2003;4:359-368.
32.
32. Reik W, Walter J. Evolution of imprinting mechanisms: The battle of the sexes begins in the zygote. Nat Genet2001;27:255-256.
33.
33. Howell CY, Bestor TH, Ding F, et al. Genomic imprinting disrupted by a maternal effect mutation in the Dnmt1 gene. Cell2001;104:829-838.
34.
34. Sleutels F, Barlow DP, Lyle R. The uniqueness of the imprinting mechanism. Curr Opin Genet Dev2000;10:229-233.
35.
35. Wilkins JF. Genomic imprinting and methylation: Epigenetic canalization and conflict. Trends Genet2005;21:356-365.
38. Li E, Beard C, Jaenisch R. Role for DNA methylation in genomic imprinting. Nature1993;366:362-365.
39.
39. Feil R, Walter J, Allen ND, et al. Developmental control of allelic methylation in the imprinted mouse Igf2 and H19 genes. Development1994;120:2933-2943.
40.
40. Constancia M, Dean W, Lopes S, et al. Deletion of a silencer element in Igf2 results in loss of imprinting independent of H19. Nat Genet2000;26:203-206.
41.
41. Weber M, Milligan L, Delalbre A, et al. Extensive tissue-specific variation of allelic methylation in the the Igf2 gene during mouse fetal development: Relation to expression and imprinting. Mech De2003;101:133-141.
42.
42. Reinhart B, Eljanne M, Chaillet JR. Shared role for differentially methylated domain of imprinted genes. Mol Cell Biol2002;22:2089-2098.
44. Feil R, Boyano MD, Allen ND, et al. Parental chromosomespecific chromatin conformation in the imprinted U2afl-rsl gene in the mouse. J Biol Chem1997;272:20893-20900.
45.
45. Smith RJ, Arnaud P, Konfortova G, et al. The mouse Zacl locus: Basis for imprinting and comparison with human ZAC. Gene2002;292:101-112.
46.
46. Reik W, Murrell A, Lewis A, et al. Chromosome loops, insulators, and histone methylation: New insights into regulation of imprinting in clusters. Cold Spring Harbor Symposia on Quantitative Biology, 2004;69:29-37.
47.
47. Weber M, Hagevge H, Aptel N, et al. Epigenetic regulation of mammalian imprinted genes: From primary to functional imprints. In: Jeanteur P, ed. Epigenetics and chromatin. Progress in molecular and subcellular biology. Berlin: Springer-Verlag; 2005:207-236.
48.
48. Wutz A, Theussl HC, Dausman J, et al. Non-imprinted Igf2r expression decreases growth and rescues the Tme mutation in mice. Development2001;128:1881-1887.
49.
49. Sleutels F, Zwart R, Barlow DP. The non-coding Air RNA is required for silencing autosomal imprinted genes. Nature2002;415:810-813.
50.
50. Bestor TH. The DNA methyltransferases of mammals. Hum Mol Genet2000;9:2395-2402.
51.
51. Chen T, Li E. Structure and function of eukaryotic DNA methyltransferases. Curr Top Dev Biol2004;60:55-89.
52.
52. Lei H, Oh SP, Okano M, et al. De novo DNA cytosine methyltransferase activities in mouse embryonic stem cells. Development1996;122:3195-3205.
53.
53. Mertineit C, Yoder JA, Taketo T, Laird DW, Trasler JM, Bestor TH. Sex-specific exons control DNA methyltransferase in mammalian germ cells. Development1998;125:889-897.
54.
54. Fatemi M, Hermann A, Pradhan S, Jeltsch A. The activity of the murine DNA methyltransferase Dnmtl is controlled by interaction of the catalytic domain with the N-terminal part of the enzyme leading to an allosteric activation of the enzyme after binding to methylated DNA. J Mol Biol2001;309:1189-1199.
55.
55. Fatemi M, Hermann A, Gowher H, Jeltsch A. Dnmt3a and Dnmtl functionally cooperate during de novo methylation of DNA, Eur J Biochem2002;269:4981-4984.
56.
56. Okano M, Bell DW, Haber DA, Li E. DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development. Cell1999;99:247-257.
57.
57. Hata K, Okano M, Lei H, Li E. Dnmt3L cooperates with the Dnmt3 family of de novo DNA methyltransferases to establish maternal imprints in mice. Development2002;129:1983-1993.
58.
58. Fedoriw AM, Stein P, Svoboda P, et al. Transgenic RNAi reveals essential function for CTCF in H19 gene imprinting. Science2004;303:238-240.
59.
59. Davis TL, Yang GJ, McCarrey JR, Bartolomei MS. The H19 methylation imprint is erased and re-established differentially on the parental alleles during male germ cell development. Hum Mol Genet2000;9:2885-2894.
60.
60. Davis TL, Trasler JM, Moss SB, Yang GJ, Bartolomei MS. Acquisition of the H19 methylation imprint occurs differentially on the parental alleles during spermatogenesis. Genomics1999;59:18-28.
61.
61. Fuks F, Burgers WA, Brehm A, Hughes-Davies L, Kouzarides T. DMA methyltransferase Dnmtl associates with histone deacetylase activity. Nat Genet2000;21:88-91.
62.
62. Murrell A, Heeson S, Reik W. Interaction between differentially methylated regions partitions the imprinted genes Igf2 and H19 into parent-specific specific chromatin loops. Nat Genet2004;36:889-893.
63.
63. Kato Y, Sasaki H. Imprinting and looping: Epigenetic marks control interactions between regulatory elements. Bioessays2005;27:1-4.
64.
64. Dean W, Ferguso-Smith A. Genomic imprinting: Mother maintains methylation marks. Curr Biol2001;11:R527-R530.
65.
65. Turner BM. Histone acetylation and an epigenetic code. Bioessays2000;22:836-845.
66.
66. Lachner M, O'Sullivan RJ, Jenuwein T. An epigenetic road map for histone lysine methylation. J Cell Sci. 2003;116:2117-2124.
67.
67. Lacoste N, Utley RT, Hunter JM, Poirier GG, Cote J. Disruptor of telomeric silencing-1 is a chromatin-specific histone H3 methyltransferase. J Biol Chem2002;277:30421-30424.
68.
68. Nguyen CT, Weisenberger DJ, Velicescu M, et al. Histone H3-lysine 9 methylation is associated with aberrant gene silencing in cancer cells and is rapidly reversed by 5-aza-2′-deoxycytidine. Cancer Res2002;62:6456-6461.
69.
69. Van Leeuwen F, Gafken PR, Gottschling DE. Dot1p modulates silencing in yeast by methylation of the nucleosome core. Cell2002;109:745-756.
70.
70. Santos F, Peters AH, Otte AP, Reik W, Dean D. Dynamic chromatin modifications characterise the first cell cycle in mouse embryos. Dev Biol2005;280:225-236.
71.
71. Adenot F, Mercier AH, Renard AP, Thompson W. Differential H4 acetylation of paternal and maternal chromatin precedes DNA replication and differential transcriptional activity in pronuclei of 1-cell mouse embryos. Development1997;124:4615-4625.
72.
72. Santos F, Hendrich B, Reik W, Dean W. Dynamic reprogramming of DNA methylation in the early mouse embryo. Dev Biol2002;41:172-182.
73.
73. Cowell IG, Aucott R, Mahadevaiah SK, et al. Heterochromatin, HP1 and methylation at lysine 9 of histone H3 in animals. Chromosoma2002;111:22-36.
74.
74. Arney KL, Bao S, Bannister AJ, Kouzarides T, Surani MA. Histone methylation defines epigenetic asymmetry in the mouse zygote. Int J Dev Biol2002;46:317-320.
75.
75. Tamaru H, Selker EU. A histone H3 methyltransferase controls DNA methylation in Neurospora crassa. Nature2001;414:277-283.
76.
76. Fuks F, Hurd PJ, Wolf D, Nan X, Bird AP, Kouzarides T. The methyl-CpG-binding protein MeCP2 links DNA methylation to histone methylation. J Biol Chem2003;278:4035-4040.
77.
77. Ginsburg M, Snow MH, McLaren A. Primordial germ cells in the mouse embryo during gastrulation. Development1990;110:521-528.
78.
78. Seki Y, Hayashi K, Itoh k, et al. Extensive and orderly reprogramming of genome-wide chromatin modifications associated with specification and early development of germ cells in mice. Dev Biol2005;278:440-458.
79.
79. Hajkova P, Erhardt S, Lane N, et al. Epigenetic reprogramming in mouse primordial germ cells. Mech Dev2002;117:15-23.
80.
80. Sato S, Yoshimizu T, Sato E, et al. Erasure of methylation imprinting of Igf2r during mouse primordial germcell development. Mol Reprod Dev2003;65:41-50.
81.
81. Ueda T, Abe K, Miura A, et al. The paternal methylation imprint of the mouse H19 locus is acquired in the gonocyte stage during foetal testis development. Genes Cells2000;5:649-659.
82.
82. Lucifero D, Mertineit C, Clarke HJ, Bestor TH, Trasler JM. Nethylation dynamics of imprinted genes in mouse germ cells. Genomics2002;79:530-538.
83.
83. Obata Y, Kono T, Hatada I. Gene silencing: Maturation of mouse fetal germ cells in vitro. Nature2002;418:497-497.
84.
84. Lucifero D, Mann MR, Bartolomei MS, Trasler JM. Genespecific timing and epigenetic memory in oocyte imprinting. Hum Mol Genet2004;13:839-849.
85.
85. Mayer W, Niveleau A, Walter J, Fundele R, Haaf T. Demethylation of the zygotic paternal genome. Nature2002;403:501-502.
86.
86. Dean W, Santos F, Reik W. Epigenetic reprogramming in early mammalian development and following somatic nuclear transfer. Semin Cell Dev Biol2003;14:93-100.
87.
87. Aoki F, Worrad DM, Schultz RM. Regulation of transcriptional activity during the first and second cell cycles in the preimplantation mouse embryo. Dev Biol1997;181:296-307.
88.
88. Johnson MH. Manipulation of early mammalian development: What does it tell us about cell lineages?Dev Biol1986;4:279-296.
89.
89. Szabo PE, Mann JR. Allele-specific expression and total expression levels of imprinted genes during early mouse development: Implications for imprinting mechanisms. Genes DEv1995;9:3097-3108.
90.
90. Rougier N, Bourchis D, Gomes DM, et al. Chromosome methylation patterns during mammalian preimplantation development. Genes Dev1998;12:2108-2113.
91.
91. Lane N, Dean W, Erhardt S, et al. Resistance of IAPs to methylation reprogramming may provide a mechanism for epigenetic inheritance in the mouse. Genesis2003;35:88-93.
92.
92. Tournaye H, Devroey P, Liu J, Nagy Z, Lissens W, Van Steirteghem A. Microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection: A new effective approach to infertility as a result of congenital bilateral absence of the vas deferens. FErtil Steril1994;61:1045-1051.
93.
93. Silber S, Van Steirteghem AC, Liu J, Nagy Z, Tournaye H, Devorey P. High fertilization and pregnancy rate after intracytoplasmic sperm injection with spermatozoa obtained from testicle biopsy. Hum Reprod1995;10:148-152.
94.
94. Tournaye H, Liu J, Nagy Z, Verheyen G, Van Steirteghem A, Devroey P. The use of testicular sperm for intracytoplasmic sperm injection in patients with necrozoospermia. Fertil Steril1996;66:331-334.
95.
95. Devroey P, Silber S, Nagy Z, et al. Ongoing pregnancies and birth after intracytoplasmic sperm injection with frozen and thawed epididymal spermatozoa. Hum Reprod1995;10:903-906.
96.
96. Tsirigotis M, Pelekanos M, Beski S, Gregorakis S, Foster C, Craft IL. Cumulative experience of percutaneous epididymal sperm aspiration (PESA) with intracytoplasmic sperm injection. J Assist Reprod GEnet1996;13:315-319.
97.
97. Devroey P, Liu J, Nagy Z, Tournaye H, Silber SJ, Van Steirteghem AC. Normal fertilization of human oocytes after testicular sperm extraction and ICSI. Fertil Steril1994;62:639-641.
98.
98. Bourne H, Watkins W, Speirs A, Baker H. Pregnancies after intracytoplasmic injection of sperm collected by fine needle biopsy of the testis. Fertil Steril1995;64:433-436.
99.
99. Tournaye H, Clasen K, Aytoz A, Nagy Z, Van Steirteghem A, Devroey P. Fine needle aspiration versus open biopsy for testicular sperm recovery: A controlled study in azoospermic patients with normal spermatogenesis. Hum Reprod1998;13:901-904.
100.
100. Florman HM, Arnoult C, Kazam IG, et al. A perspective on the control of mammalian fertilization be egg-activated ion channel in sperm: A tale of two channels. Biol Reprod1998;59:12-16.
101.
101. Check JH, Bollendorf A, Press M, Blue T. Standard sperm morphology as a predictor of male fertility potential. Arch Androl1992;28:39-41.
102.
102. Check ML, Bollendorf A, Check JH, Katsoff D. Reevaluation of the clinical importance of evaluating sperm morphology using strict criteria. Arch Androl2002;48:1-3.
103.
103. Van Assche E, Bonduelle M, Tournaye H, et al. Cytogenetics of infertile men. Hum REprod1996;11 (Suppl 4):1-26.
104.
104. Yoshida A, Miura K, Shirai M. Cytogenetic survey of 1007 infertile males. Int J Urol1997;58:166-176.
105.
105. Mateizel I, Verheyen G, Van Assche E, Tournaye H, Liebaers I, Van Steirteghem A. FISH analyses of chromosome X, Y and 18 abnormalities in testicular sperm from azoospermic patients. Hum Reprod2002;17:2249-2257.
106.
106. Deveroey P, Van Sterirteghem A. A review of ten years experience of ICSI. Hum Rep Update2004;10:19-28.
107.
107. Marques CJ, Carvalho F, Sousa M, et al. Genomic imprinting in disruptive spermatogenesis. Lancet2004;363:1700-1702.
108.
108. Reik W, Dean W, Walter J. Epigenetic reprogramming in mammalian development. Science2001;293:1089-1093.
109.
109. Schieve LA, Meikle SF, Ferre C, Peterson HB, Jeng G, Wilcox LS. Low and very low birth weight in infants conceived with use of assisted reproductive technology. N Engl J Med2002;46:731-737.
110.
110. Sinclair K, Young LE, Wilmut I. In-utero overgrowth in ruminants following embryo culture: Lessons from mice and a warning to men. Hum Reprod2000;15:68-86.
111.
111. Renard JP, Chastant S, Chesne P. Lymphoid hypoplasia and somatic cloning. Lancet1999;353:1489-1491.
112.
112. Young LE, Fernandes K, McEvoy TG, et al. Epigenetic change in IGF2R is associated with fetal overgrowth after sheep embryo culture. Nat Genet2001;27:153-154.
113.
113. Khosla S, Dean W, Brown D, Reik W, Fell R. Culture of preimplantation mouse embryos affects fetal development and the expression of imprinted genes. Biol Reprod2001;64:918-926.
114.
114. Doherty AS, Mann MR, Tremblay KD, Bartolomei MS, Schultz RM. Differential effects of culture on imprinted H19 expression in the preimplantation mouse embryo. Biol Reprod2000;62:1526-1535.
115.
115. Lawitts JA, Biggers JD. Optimization of mouse embryo culture media using simplex methods. J Reprod Fertil1991;91:543-556.
116.
116. Aiken RJ, Clarkson JS, Fishel S. Generation of reactive oxygen species, lipid peroxidation and human sperm function. Biol Reprod1989;41:183-187.
117.
117. Kerjean A, Couvert P, Heams T, et al. In vitro follicular growth affects oocyte imprinting establishment in mice. Eur J Hum Genet2003;11:493-496.
118.
118. Shi W, Haaf T. Aberrant methylation patterns at the two-cell stage as an indicator of early developmental failure. Mol Reprod Dev2002;63:329-334.
119.
119. Setti PE, Albani E, Novara PV, Cesana A, Morreale G. Cryopreservation of supernumerary oocytes in IVF/ICSI cycles. Hum Reprod2006;21:370-375.
120.
120. Caglar GS, Hammadeh M, Asimakopoulos B, Nolettos N, Diedrich K, Al-Hassani S. In vivo and in vitro decondensation of human sperm and assisted reproduction technologies. In Vivo2005;19:623-630.
121.
121. Asimakopoulos B, Nikolettos N, Al-Hassani S. Is there a place for round and elongated spermatids injection in assisted reproduction?Iran J Reprod Med2003;1:1-6.
122.
122. Kerjean A, Dupont J, Vasseur C, et al. Establishment of the paternal methylation imprint of the human H19 and MEST/PEG1 genes during spermatogenesis. Hum Mol Genet2000;9:2183-2187.
123.
123. War WS, Coffey DS. DNA packaging and organization in mammalian spermatozoa: Comparison with somatic cells. Biol Reprod1991;44:569-574.
124.
124. Dadoune JP. The nuclear status of human sperm cells. Micron1995;26:323-345.
125.
125. Aoki F, Worrad DM, Schultz RM. Regulation of transcriptional activity during during the first and second cell cycles in the preimplantation mouse embryo. Dev Biol1997;181:296-307.
126.
126. Poccia D. Remodeling of nucleoproteins during gametogenesis, fertilization and development. Int Rev Cytol1986;105:1-65.
127.
127. Huang TT, Kosower NS and Yanagimachi R. Thiol-disulfide status and acridine orange fluorescence of mammalian sperm nuclei. J Androl1992;13:342-348.
128.
128. Bedford JM, Calvin HI. The occurrence and possible functional significance of S-S crosslinks in sperm heads, with particular reference to eutherian mammals. J Exp Zool1974;188:137-156.
129.
129. Aitken J. The biochemistiy and physiology of human spermatozoa: Consequences for fertility and sterility. In: Van Blerkom J, ed. The biological basis of early human reproductive failure: Application to medically assisted conception and the treatment of infertility. New York: Oxford University press, 1994:252-282.
130.
130. Dozortsev D, De Sutler P, Dhont M. Behaviour of Spermatozoa in human oocytes displaying no or one pronucleus after intracytoplasmic sperm injection. Hum Reprod1994;9:2139-2144.
131.
131. Tesrik J. Oocyte activation after intracytoplasmic injection of mature and immature sperm cells. Hum Reprod1998;13 (Suppl):117-127.
132.
132. Ariel M, Cedar H, McCarrey J. Developmental Changes in methylation of spermatogenesis-specific genes include reprogramming in the epididymis. Nat Genet1994;7:59-63.
133.
133. Zeck H, Vanderzwalmen P, Prapas Y, Lejeune B, Duba E, Schoysman R. Congenital malformations after intracytoplasmic injection of spermatids. Hum Reprod2000;15:969-971.
134.
134. Viedan K, Isik AZ, Delilbasi L. Development of blastrocyst stage embryos after round spermatid injection in patients with complete spermiogenesis failure. J Assist Reprod Genet2001;18:78-86.
135.
135. Bonduelle M, Liebaers I, Deketelaere V, et al. Neonatal data on a cohort of 2889 infants born after ICSI (1991-1999) and of 2995 infants born after IVF (1983-1999). Hum Reprod2002;17:671-694.
136.
136. Sutcliffe AG, Taylor B, Saunders K, Thornton S, Leiberman BA, Grudzinskas JG. Outcome in the second year of life after in-vitro fertilisation by intracytoplasmic sperm injection: A UK case-control study. Lancet2001;357:2080-2084.
137.
137. Zadori ZJ, Kozinszky Z, Orvos H, Katona M, Kaali SG, Pal A. The incidence of major birth defects following in vitro fertilization. J Assist Reprod Genet2003;20:131-132.
138.
138. Ziyyat A, Lefevre A. Differential gene expression in preimplantation embryos from mouse oocytes injected with round spermatids or spermatozoa. Hum Reprod2001;16:1449-1456.
139.
139. Preece MA. The genetics of the Silver-Russell syndrome. Rev Endocr Metab Disord2002;3:369-379.
140.
140. Wey E, Bartholdi D, Riegel M, et al. Mosaic imprinting defect in a patient with an almost typical expression of the Prader-Willi syndrome. Eur J Hum Genet2005;13:273-277.
141.
141. Makedonski K, Abuhatzira L, Kaufman Y, et al. MeCP2 deficiency in Rett syndrome causes epigenetic aberrations at the PWS/AS imprinting center that affect UBE3A expression. Hum Mol Genet2005;14:1049-1058.
142.
142. Barlow DH. The children of assisted reproduction—The need for an ongoing debate. Hum Reprod2002;17:1133-1134.
143.
143. Kovalevsky G, Rinaudo P and Coutifaris C. Do assisted reproductive technologies cause adverse fetal outcomes?Fertil Steril2003;79:1270-1272.
144.
144. Powell K. Fertility treatments: Seeds of doubt. Nature2003;422;656-658.
145.
145. Buiting K, Gross S, Lich C, Gillessen-Kaesbach G, el-Maari O, Horsthemake B. Epimutations in Prader-Willi and Angelman syndromes: A molecular study of 136 patients with an imprinting defect. Am J Hum Genet2003;72:571-577.
147. Judson H, Hayward BE, Sheridan E, et al. A global disorded of imprinting in the human female germ line. Nature2002;416:539-542.
148.
148. John RM, Surani MA. Agouti germ line gets acquisitive. Nature Genet1999;23:254-256.
149.
149. Lumey LH. Decreased birthweights in infants after maternal in utero exposure to the Dutch famine of 1944-1945. Paediatr Perinat Epidemiol1992;6:240-253.
150.
150. Gosden R. Trasler J, Lucifero D, Faddy M. Rare congenital disorders, imprinted genes, and assisted reproductive technology. Lancet2003;7:1975-1977.
151.
151. Ludwig M, Diedrich K. Follow-up of children born after assisted reproductive technologies. Reprod Biomed Online2005;5:317-322.
152.
152. Lambert RD. Safety issues in assisted reproductive technology: Aetiology of health problems in singleton ART babies. Hum Reprod2003;18:1987-1991.
153.
153. Bhattacharya S, Hamilton MP, Shaaban M, et al. Conventional ini-vitro fertilisation versus intracytoplasmic sperm injection for the treatment of non-male-facetor infertility: A randomised controlled trial. Lancet2001;357:2075-2079.
154.
154. Van Steirteghem A, Collins J. Evidence-based medicine for treatment: An in vitro fertilization trial. Semin Reprod Med2003;21:49-54.
155.
155. Hammadeh ME, Stieber M, Haidl G, Schmidt W. Association between sperm cell chromatin condensation, morphology based on strict criteria, and fertilization, clkeavage and pregnancy rates in an IVF program. Andrologia1998;30:29-35.
156.
156. Host E, Lindenberg S, Smidt-Jensen S. The role of DNA strand breaks in human spermatozoa used for IVF and ICSI. Acta Obstet Gynecol Scand2000;79:559-563.
157.
157. Twigg JP, Irvine DS, Aitken RJ. Oxidative damage to DNA human spermatozoa does not preclude the pronucleus formation at intracytoplasmic sperm injection. Hum Reprod1998;13:1864-1871.
158.
158. Chan AW, Luetjens CM, Dominko T, et al. Foreign DNA transmission by ICSI: Injection of spermatozoa bound with exogenous DNS results in embryonic GFP expression and live rhesus monkey births. Mol Hum Reprod2000;6:26-33.
159.
159. Chan AW, Luetjens CM, Dominko T, et al. Transgen ICSI reviewed: Foreign DNA transmission by intracytoplasmic sperm injection in rhesus monkey. Mol Reprod Dev2005;56(2 Suppl):325-328.
160.
160. Kamischke A, Gromoll J, Simoni M, Behre HM, Nieschlag E. Transmission of a Y chromosomal deletion involving the deleted in azoospermia (DAZ) and chromodomain (CDY1) genes from father to son through intracytoplasmic sperm injection: Case report. Hum Reprod1999;14:2320-2322.
