Scientists at the University of Oxford have recently discovered the presence of exosomes in males' seminal fluid in Drosophila melanogaster (fruit fly) which helps to ensure their reproductive success with females .
This mechanism takes place during mating, when male exosomes produced in response to BMP (bone morphogenetic protein) signaling, fuse to sperm and interact with the female reproductive tract epithelia (see Figure 1 below). Movement of the male's exosomes were tracted using a fluorescent exosomal marker during the investigation to allow easy visualization and exosome analysis.
Figure 1. Left: The female fruit fly's reproductive tract. Right: A male's exosome (green circle) interacting with the female reproductive tract (as indicated by the arrow) after mating. photo credit: Corrigan et al. (2014).
This evolutionarily conserved process acts to reprogram the female's behavior and prevent her from re-mating with other males. The authors noted that a reduction in the number of exosomes led to an increased chance of the female fly to re-mate, reinforcing this finding. The discovery of exosomes involved in this biological tool is an exciting discovery as researchers were unsure how signaling factors secreted from the male were delivered to the female to cause a behavioral change.
The interesting link observed between BMP signaling and exosome release in the fruit fly's reproductive system suggests the possibility of a link in human reproductive cancers.
 Corrigan, L. et al. BMP-regulated exosomes from Drosophila male reproductive glands reprogram female behavior. Aug 2014. The Journal of Cell Biology. 206: 671-688.