Ultrastructural examination of the insemination reaction in Drosophila

Henar Alonso-Pimentel, Leslie P. Tolbert, William B. Heed

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The insemination reaction is a swelling of the female vagina caused by the male ejaculate. This postmating phenomenon is common among species in the genus Drosophila. It could act as a plug securing male paternity. It is not clear, however, what benefits it provides to the female. The structure formed in the female vagina is expelled in some species and disappears gradually in others suggesting different phenomena. Based on ultrastructural examination of the vaginal contents of five Drosophila species (D. mettleri, D. nigrospiracula, D. melanogaster, D. mojavensis, and D. hexastigma), we propose three terms to describe these vaginal structures: the sperm sac, the mating plug, and the true insemination reaction. Each term describes a distinct structure associated with a specific female postmating behavior. This study questions the concept of the insemination reaction as a single phenomenon and discusses its possible functions from an evolutionary perspective.

Original languageEnglish (US)
Pages (from-to)467-479
Number of pages13
JournalCell & Tissue Research
Issue number3
StatePublished - Mar 1994


  • Drosophila (Insecta)
  • Evolution
  • Insemination reaction
  • Paragonia
  • Postmating behavior
  • Sexual selection
  • Sperm competition
  • Vagina

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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