Amaze1990
Fertilization is an essential process in sexual reproduction which involves the union of two specialized cells called the gametes to form a zygote. This then develops to form the new organism. During the process of fertilization innumerable number of sperms hit the surface of the eggs. But only one sperm succeeds in fertilizing it and the rest are repelled from the surface of the egg. This is done by the modification of cell envelope & extracellular matrix besides altering the metabolic activity of the zygote or embryo. Various metabolic changes occur after the zygote is formed. This includes the respiratory burst hydrogen peroxide production activation of oxidases peroxidase alterations in the redox status changes in the activity of redox-sensitive transcription factors etc. Besides these an embryo-derived paf (1-o-alkyl-2-acetyl-sn-gylcero-3-phosphocholine) is synthesized and its release involves the binding to extracellular albumin which protects its enzymatic degradation (ONeill C, 1985). The change in the redox state affects the activity of redox-sensitive transcription factors that may alter gene expression patterns. Besides, this change in the metabolic status also, is responsible for the spatial differences in cell activity especially after compaction and major embryonic events such as fertilization genome activation and cellular differentiation (AJ Harvey et al, 2002). Multiple variations that occurs during this stage are found throughout phylogeny (Wessel G.M.et al., 2001; Shapiro B.M. et al, 1989).