Glow-in-the-dark sperm

Scott Pitnick and his colleagues from Syracuse University have created fruit flies (Drosophila melanogaster) that have red or green glowing sperm. The researchers were able to follow the sperm of competing males through the females’ reproductive tracts.

Photo credit: Scott Pitnick, Syracuse University

Reproductive tract of female D. melanogaster initially mated to green sperm male then remated to red sperm male. Green sperm heads have left the storage organs and can be seen mixing with red sperm heads in the bursa.

Among their findings: the sperm from both males traveled through the storage organs and reached the eggs at rates unrelated to the time of copulation. It was abundance, rather than timing that mattered.