Activation of fertilized and nuclear transfer eggs.
In all animal species, initiation of embryonic development occurs shortly after the joining together of the gametes from each of the sexes. The first of these steps, referred to as "egg activation", is a series of molecular events that results in the syngamy of the two haploid genomes and the beginning of cellular divisions for the new diploid embryo. For many years it has been known that the incoming sperm drives this process, as an unfertilized egg will remain dormant until it can no longer sustain normal metabolic processes. Until recently, it was also believed that the sperm was the only cell capable of creating a viable embryo and offspring. Recent advances in cell biology have allowed researchers to not only understand the molecular mechanisms of egg activation, but to exploit the use of pharmacological agents to bypass sperm-induced egg activation for the creation of animals by somatic cell nuclear transfer. This chapter will focus on the molecular events of egg activation in mammals as they take place during fertilization, and will discuss how these mechanisms are successfully bypassed in processes such as somatic cell nuclear transfer.
Malcuit
Christopher
C
Department of Veterinary and Animal Sciences, Paige Laboratory, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Fissore
Rafael A
RA
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology; D019976:Cloning, Organism / Q000379:methods* / Q000639:trends; D046149:Embryo Culture Techniques / Q000379:methods; D047108:Embryonic Development / Q000235:genetics*; D005260:Female; D005306:Fertilization / Q000502:physiology; D006801:Humans; D008297:Male; D053652:Nuclear Transfer Techniques / Q000639:trends*; D010063:Ovum / Q000254:growth & development* / Q000378:metabolism; D035845:Research Embryo Creation / Q000379:methods; D013094:Spermatozoa / Q000378:metabolism