Cytoskeletal Functions, Defects, and Dysfunctions Affecting Human Fertilization and Embryo Development

Heide Schatten1 and Qing-Yuan Sun2

1DepartmentofVeterinaryPathobiology, UniversityofMissouri, Columbia, MO, USA 2State Key Laboratory ofReproductive Biology, Institute ofZoology, Chinese Academy of Sciences, Beijing, China

Introduction

Reproductive disorders including subfertility, infertility, fertility disorders, developmental abnormalities, spontaneous abortion, and embryo loss are on the rise worldwide, which has led to an increase in in vitro fertilization (IVF) clinics (reviewed in Qiao et al., 2014). An increasing number of couples seek medical help in IVF clinics to overcome reproductive difficulties and have children. IVF and other assisted reproductive technologies (ART) have become a significant part of human reproduction with already one in 50 children being born through ART (Manipalviratn et al., 2009) and the demand for ART is steadily increasing. However, the overall success rate for ART is still low (35-40% in many clinics; up to 60% in others) (US Department of Health and Human Services, 2006; Assisted Reproductive National Summary Report, 2013; Jain et al., 2004; Leniaud et al., 2008; Stern et al., 2009; Stillman et al., 2009) and depends on a number of different factors and is in part is related to an incomplete understanding of cell and molecular criteria to evaluate embryo quality before transfer into the mother’s uterus. As detailed in the Assisted Reproductive National Summary Report (2013), based on the CDC’s 2013 Fertility Clinic Success Rates Report, in 2013 there were 190,773 ART cycles performed at 467 reporting clinics in the United States.

Human Reproduction: Updates and NewHorizons, First Edition. Edited by Heide Schatten. © 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.

Between 1 and 1.5 million human embryos are produced annually for clinical IVF programs in the United States. The embryos vary significantly in their potential for successful implantation and development (Bielanska et al., 2002; Baart et al., 2006; Vanneste et al., 2009, 2011; Johnson et al., 2010) but optimal criteria to predict embryo developmental potential and to select those embryos with the highest developmental potential for transfer are largely missing, resulting in transfer of embryos that are prone to miscarriage. Embryo loss is frequently associated with pre-implantation embryo defects but little is known about the underlying reasons for implantation failure. Achieving optimal embryo quality with the best potential for embryo development begins with oocyte maturation.

Oocyte quality depends on accurate nuclear maturation and cytoplasmic maturation for fertilization to be successful. After fertilization, in humans and most other non-rodent mammalian species, unlike in rodent species such as the mouse, the sperm centriole-centrosome complex is essential for successful fertilization and for accurate formation of the mitotic apparatus during first and all subsequent cell divisions, which will be detailed in specific sections of this chapter.

In the following sections we will focus on cytoskeletal organization, regulation, dynamics, and functions that are critically important for mammalian oocyte maturation, fertilization, and pre-implantation embryo development

 
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