Atypical decondensation of the sperm nucleus, delayed replication of the male genome, and sex chromosome positioning following intracytoplasmic human sperm injection (ICSI) into golden hamster eggs: does ICSI itself introduce chromosomal anomalies?

OBJECTIVE To examine nuclear decondensation, positioning of sex chromosomes, and the S-phase in human sperm nuclei following intracytoplasmic sperm injection (ICSI) into hamster eggs. DESIGN Prospective analysis of hamster eggs and human sperm following ICSI. SETTING Division of Reproductive Sciences, Oregon Health Sciences University and Oregon Regional Primate Research Center. PATIENT(S) Fertile donor sperm from a commercial source. INTERVENTION(S) Human sperm were examined by immunofluorescence stain, bromodioxyuridine (BrdU) uptake assay and fluorescence in situ hybridization following ICSI into hamster eggs. MAIN OUTCOME MEASURE(S) Immunostaining and fluorescence in situ hybridization. RESULT(S) Decondensation of human sperm nuclei occurred initially in the basal region, and perinuclear theca of sperm persisted around the condensed apical region. In some sperm nuclei, following ICSI the sex chromosomes were in the apical region, remaining condensed for longer than in the basal region. S-phase entry of human sperm nuclei following ICSI was delayed compared to the zona-free hamster egg penetration assay. CONCLUSION(S) These results force questions about the mechanism of male pronuclear formation after ICSI and suggest new strategies for understanding the basis of chromosomal anomalies leading to birth defects as well as continuing improvements in the safety and efficacy of infertility therapies.

[1]  L. Gordon,et al.  Analysis of the first cell cycle in the cross between hamster eggs and human sperm. , 1989, Gamete research.

[2]  G. Schatten,et al.  Cell and Molecular Biological Challenges of ICSI: ART before Science? , 1998, Journal of Law, Medicine & Ethics.

[3]  P. De Sutter,et al.  Effect of post-ovulatory age and calcium in the injection medium on the male pronucleus formation and metaphase entry following injection of human spermatozoa into golden hamster oocytes. , 1999, Molecular human reproduction.

[4]  B. Bavister,et al.  A consistently successful procedure for in vitro fertilization of golden hamster eggs. , 1989, Gamete research.

[5]  G. Schatten,et al.  Fate of the sperm mitochondria, and the incorporation, conversion, and disassembly of the sperm tail structures during bovine fertilization. , 1996, Biology of reproduction.

[6]  G. Schatten,et al.  Non-random chromosome positioning in human sperm and sex chromosome anomalies following intracytoplasmic sperm injection , 1999, The Lancet.

[7]  D. Wolf,et al.  Penetration of the zona-free hamster egg by human sperm. , 1980, Fertility and sterility.

[8]  R. Yanagimachi.  Zona‐free hamster eggs: Their use in assessing fertilizing capacity and examining chromosomes of human spermatozoa , 1984 .

[9]  R Yanagimachi,et al.  Analysis of mouse oocyte activation suggests the involvement of sperm perinuclear material. , 1998, Biology of reproduction.

[10]  H. Tournaye,et al.  Seven years of intracytoplasmic sperm injection and follow-up of 1987 subsequent children. , 1999, Human reproduction.

[11]  G. Schatten,et al.  The removal of the sperm perinuclear theca and its association with the bovine oocyte surface during fertilization. , 1997, Developmental biology.

[12]  B. Zirkin,et al.  DNA synthesis following microinjection of heterologous sperm and somatic cell nuclei into hamster oocytes. , 1987, Gamete research.

[13]  Z. Nagy,et al.  Ultrastructure of gametes after intracytoplasmic sperm injection. , 1998, Human reproduction.

[14]  G. Schatten,et al.  Intracytoplasmic sperm injection for Rhesus monkey fertilization results in unusual chromatin, cytoskeletal, and membrane events, but eventually leads to pronuclear development and sperm aster assembly. , 1996, Human reproduction.

[15]  P. De Sutter,et al.  Chromatin decondensation, pronucleus formation, metaphase entry and chromosome complements of human spermatozoa after intracytoplasmic sperm injection into hamster oocytes. , 1998, Human reproduction.

[16]  S. Ng,et al.  Influence of sperm plasma membrane destruction on human sperm head decondensation and pronuclear formation. , 1999, Archives of andrology.

[17]  G. Schatten,et al.  Microtubule and chromatin configurations during rhesus intracytoplasmic sperm injection: successes and failures. , 1996, Biology of reproduction.

[18]  G. Schatten,et al.  Unique checkpoints during the first cell cycle of fertilization after intracytoplasmic sperm injection in rhesus monkeys , 1999, Nature Medicine.

[19]  G. Schatten,et al.  Sperm Aster Formation and Pronuclear Decondensation During Rabbit Fertilization and Development of a Functional Assay for Human Sperm1 , 2000, Biology of reproduction.

[20]  G. Schatten.  The centrosome and its mode of inheritance: the reduction of the centrosome during gametogenesis and its restoration during fertilization. , 1994, Developmental biology.

[21]  R. Oko,et al.  Protein composition of the perinuclear theca of bull spermatozoa. , 1994, Biology of reproduction.

[22]  M. Schmid,et al.  Determination of Y chromosome aneuploidy in human sperm nuclei by nonradioactive in situ hybridization. , 1990, American journal of human genetics.