Zygote

Table of Contents - 1994 - Volume 2, Issue 04  

Article

Sperm activation in species with external fertilisation

Elisabetta Tosita1

a1 Stazione Zoologica, Villa Comunale, I-80121 Naples, Italy

The spermatoozoon is an excitable cell that responds to specific effectors by rapidly changing its behaviour. In species with external fertilisation, spermatozoa are stored in a quiescent state in the testis, but within seconds after spawning, dilution into water triggers several activation events such as increases in motility and respiration. In some species, these are followed by the acrosome reaction, an exocytotic process that allows the spermatozoon to penetrate the egg investments and activate the egg (Dale, 1983). The majority of information on sperm activation has come from the sea urchin; secondarily teleosts and starfish have proved to be useful models.

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