This beautiful image of a skate fish embryo reveals something truly extraordinary about the scales on its body. As University of Cambridge biologist Andrew Gillis explains, they are, in fact, quite similar to human teeth. They're even controlled by genes similar to those that control tooth growth in humans. You may never look at fish scales in the same way again.

Says Gillis:

This is a picture of the head of an embryonic skate (Leucoraja erinacea). A skate is a cartilaginous fish, closely related to sharks and stingrays. This embryo has been stained with dyes that colour the skeleton - cartilage is blue, and mineralised tissue is red - and then cleared with chemicals to make it transparent. The result is a specimen that shows the complex shape and arrangement of different skeletal tissues during embryonic development. I use this staining procedure to visualise the skeleton following experimental manipulation. This allows me to investigate how different genes and proteins are involved in controlling the formation and growth of different skeletal tissues in these fishes.

The skate image is approximately 3 cm across.

Music by Peter Nickalls

This is the ninth in a series of videos called Under the Microscope, which io9 is posting in partnership with scientists at University of Cambridge. Under the Microscope is a collection of videos that capture glimpses of the natural and artificial world in stunning close-up. They will be released every Monday and Thursday for the next couple of months, and you can see the whole series here.