Cellular and genetic analysis of oocytes and embryos in a human case of spontaneous oocyte activation

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Catherine M.H. Combelles1,*, William G. Kearns2, Janis H. Fox3 and Catherine Racowsky3

1Biology Department, Middlebury College, Middlebury, VT 05753, USA

2Shady Grove Center for Preimplantation Genetics, Department of Gynecology and Obstetrics, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA

3Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA *Correspondence address. E-mail: ccombell{at}middlebury.eduReceived October 4, 2010. Revision received November 18, 2010. Accepted November 25, 2010. Unusual and consistent defects in infertility patients merit attention as these may indicate an underlying genetic abnormality, in turn necessitating tailored management strategies. We describe a case of repeated early pregnancy loss from in vivo conceptions, followed by cancelled embryo transfers after one IVF and one ICSI/PGD cycle. Following the unexpected presence of cleaved embryos at the fertilization check in the first IVF attempt, oocytes and embryos were subsequently analyzed in an ICSI/PGD case. Part of the oocyte cohort was fixed at retrieval for a cellular evaluation of microtubules, microfilaments and chromatin. The remaining oocytes were injected with sperm, and resultant embryos were biopsied for genetic analysis by fluorescence in situ hybridization (FISH), single-nucleotide polymorphism (SNP) microarray for 23 chromosome pairs, as well as with PCR for sex chromosomes. The presence of interphase microtubule networks and pronuclear structures indicated that oocytes were spontaneously activated by the time of retrieval. FISH revealed aneuploidy in all seven blastomeres analyzed, with all but two lacking Y chromosomes. Microarray SNP analysis showed an exclusively maternal origin of all blastomeres analyzed, which was further confirmed by PCR. From our multi-faceted analyses, we conclude that spontaneous activation, or parthenogenesis, was probably the pathology underlying our patient's recurrent inability to maintain a normal pregnancy. Such analyses may prove beneficial not only in diagnosing case-specific aberrations for other patients with similar or related failures, but also for furthering our general understanding of oocyte activation.

© The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com This ArticleHum. Reprod. (2011) 26 (3): 545-552. doi: 10.1093/humrep/deq363 First published online: January 11, 2011

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Increased zona pellucida thickness and meiotic spindle disruption in oocytes from cigarette smoking mice

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Phoebe C. Jennings1, Julie A. Merriman1, Emma L. Beckett1,2, Philip M. Hansbro1,2 and Keith T. Jones1,*

1School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia

2Centre for Asthma and Respiratory Disease and Hunter Medical Research Institute, The University of Newcastle, Callaghan, NSW 2308, Australia *Correspondence address. Tel: +61-2-49-21-66-82; Fax: +61-2-49-21-79-03; E-mail: keith.jones{at}newcastle.edu.auReceived October 5, 2010. Revision received December 13, 2010. Accepted December 17, 2010. BACKGROUND The precise effects of cigarette smoking on female fertility have not yet been clearly defined. We have used a mouse model that mimics human smoking and is able to control for variables that may confound clinical studies to assess the impact of chronic smoking on the quality of mouse oocytes.

METHODS Mice received cigarette smoke directly to their lungs for 12 weeks. Lung tissue was analyzed for emphysematous changes and cumulus enclosed oocytes (CEOs) were recovered to study their quality. CEOs were in vitro matured, fixed and stained for chromatin and tubulin. Meiotic spindles, chromatin and the zona pellucida were all examined using confocal microscopy.

RESULTS After 12 weeks of cigarette smoking, mice developed alveolar tissue damage that was determined by an increase in destructive index of the lung parenchyma. The numbers of oocytes recovered and the rates of oocyte maturation were not significantly different from non-smoking mice. However, oocytes from smoking mice had a significantly thicker zona pellucida along with shorter and wider meiotic spindles. Furthermore in total, almost a quarter of oocytes from smoking mice were abnormal as assessed by either errors in chromosomal congression or spindle shape.

CONCLUSIONS We have used a novel model of inhalational cigarette smoking to show that chronic smoking has a detrimental effect on oocyte quality, and this can be observed even though oocytes are removed from the ovary and cultured in vitro.

© The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com This ArticleHum. Reprod. (2011) 26 (4): 878-884. doi: 10.1093/humrep/deq393 First published online: January 12, 2011

Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

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