Egg fertilization and maturation

There is considerable evidence that calcium acts as a primary trigger for egg maturation and fertilization in several phyla. Calcium regulation has been demonstrated or suggested for numerous specific events in fertilization, including sperm motility, the acrosome reaction, sperm-egg binding and fusion and metabolic activation of egg, etc. However, very little is known concerning the mechanisms whereby calcium exerts its effects. 

One of the best studied systems concerning the role of calcium in egg fertilization is the sea urchin egg [123]. Upon fertilization, two ion fluxes occur in short prere-plicative phase which are obligatory for the subsequent initiation of processes, including DNA synthesis [124], The first is an internal surge of calcium ions at about 0-3 s post fertilization, and second is the efflux of hydrogen ion coupled to an influx of Na+ resulting in the alkalization of egg cytoplasm [125], 

Whatever the mechanism of growth factor induced transient rise in intracellular calcium (internal release or influx), the key question is the physiological role of cal- 

Rasmussen, H. (1981) Calcium and c-AMP as synarchic messengers. John Wiley and Sons, New York. 

(1986) Calcium and the Cell. (Ciba Foundation) Symposium 122, pp. 1-4. Wiley, Chichester. 

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