From ejaculation to fertilisation, sperm cells embark on an adventure, moving along the walls of the uterus and cervix until they reach their prize: an egg cell in the oviduct. Not only do sperm have to travel a relatively huge distance to reach the egg, they also have to swim through fluids of variable speeds and thicknesses. Researchers set up an ‘assault course’, where, using a technique called microfluidics, they saw the travelling in action. They observed sperm wiggling in a spiral motion upstream, avoiding the centre of the tubes where flow was fastest. When exposed to thicker fluids, sperm turn and quickly readjust to the flow – seen here as an arc-shaped track. Sperm also grouped together, working collectively to swim faster, rather than in competition with each other. These observations provide new insights into the fertilisation process and could help with the design of more effective artificial insemination methods.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.