Dynamic resolution of acrosomal exocytosis in human sperm

CLAIRE HARPER, Joanne A Cummerson, Michael R H White, Stephen J Publicover, Peter M Johnson

Research output: Contribution to journalArticle (journal)peer-review

45 Citations (Scopus)


An essential step in mammalian fertilisation is the sperm acrosome reaction (AR) - exocytosis of a single large vesicle (the acrosome) that surrounds the nucleus at the apical sperm head. The acrosomal and plasma membranes fuse, resulting in both the release of factors that might facilitate penetration of the zona pellucida (which invests the egg) and the externalisation of membrane components required for gamete fusion. Exocytosis in somatic cells is a rapid process - typically complete within milliseconds - yet acrosomal enzymes are required throughout zona penetration - a period of minutes. Here, we present the first studies of this crucial and complex event occurring in real-time in individual live sperm using time-lapse fluorescence microscopy. Simultaneous imaging of separate probes for acrosomal content and inner acrosomal membrane show that rapid membrane fusion, initiated at the cell apex, is followed by exceptionally slow dispersal of acrosomal content (up to 12 minutes). Cells that lose their acrosome prematurely (spontaneous AR), compromising their ability to penetrate the egg vestments, are those that are already subject to a loss of motility and viability. Cells undergoing stimulus-induced AR (progesterone or A23187) remain viable, with a proportion remaining motile (progesterone). These findings suggest that the AR is a highly adapted form of exocytosis.

Original languageEnglish
Pages (from-to)2130-5
Number of pages6
JournalJournal of Cell Science
Issue numberPt 13
Publication statusPublished - 1 Jul 2008


  • Acrosome/physiology
  • Acrosome Reaction
  • Animals
  • Exocytosis
  • Female
  • Humans
  • Kinetics
  • Male
  • Membrane Fusion
  • Microscopy, Fluorescence
  • Sperm Capacitation
  • Sperm-Ovum Interactions
  • Spermatozoa/physiology
  • Zona Pellucida/physiology


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