A soluble extract from human spermatozoa activates ascidian oocytes

Martin Wilding, Keiichiro Kyozuka, Gian Luigi Russo, Elisabetta Tosti, Brian Dale

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


A soluble extract from human spermatozoa induced calcium oscillations and extrusion of the first polar body when injected into oocytes of the ascidian Ciona intestinalis. The properties of calcium oscillations and time of polar body extrusion precisely mimic oocyte activation induced by C. intestinalis sperm or sperm extracts. The data suggest that human sperm extracts can activate oocytes of different phyla by the same mechanism as homologous spermatozoa. Injection of inositol 1,4,5-trisphosphate (IP3) into C. intestinalis oocytes mimicked to some extent the initial stages of oocyte activation, but the results demonstrate that ascidian oocyte activation by human sperm extract cannot be explained solely in terms of IP3-induced calcium release. Injection of other calcium releasing second messengers, cyclic adenosine diphosphate ribose, or calcium ions, does not lead to oocyte activation or release intracellular calcium in ascidian oocytes. It was concluded that human spermatozoa contain one or more molecules that can trigger intracellular calcium release in oocytes from different phyla.

Original languageEnglish
Pages (from-to)329-336
Number of pages8
JournalDevelopment Growth and Differentiation
Issue number3
Publication statusPublished - 1997


  • Ascidian
  • Calcium
  • Human sperm
  • Oocyte activation
  • Sperm factor

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology


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