How is it that fertilized chicken eggs manage to resist fracture from the outside, while at the same time, are weak enough to break from the inside during chick hatching? It’s all in the eggshell’s nanostructure, according to a new study led by McGill University scientists.
The findings, reported today in Science Advances, could have important implications for food safety in the agro-industry.
Birds have benefited from millions of years of evolution to make the perfect eggshell, a thin, protective biomineralized chamber for embryonic growth that contains all the nutrients required for the growth of a baby chick. The shell, being not too strong, but also not too weak (being “just right” Goldilocks might say), is resistant to fracture until it’s time for hatching.
But what exactly gives bird eggshells these unique features?
To find out, Marc McKee’s research team in McGill’s Faculty of Dentistry, together with Richard Chromik’s group in Engineering and other colleagues, used new sample-preparation techniques to expose the interior of the eggshells to study their molecular nanostructure and mechanical properties.
“Eggshells are notoriously difficult to study by traditional means, because they easily break when we try to make a thin slice for imaging by electron microscopy,” says McKee, who is also a professor in McGill’s Department of Anatomy and Cell Biology.