Yogurt-eating mice have larger testicles and "mouse swagger"

A study at MIT involving mice fed a diet of vanilla yogurt with probiotics yielded interesting and unanticipated results:

First, the scientists noticed that the yogurt-eating mice were incredibly shiny. Using both traditional histology techniques and cosmetic rating scales, the researchers showed that these animals had 10 times the active follicle density of other mice, resulting in luxuriantly silky fur.

Then the researchers spotted some­thing particular about the males: they projected their testes outward, which endowed them with a certain “mouse swagger,” Erdman says. On measuring the males, they found that the testicles of the yogurt consumers were about 5 percent heavier than those of mice fed typical diets alone and around 15 percent heavier than those of junk-eating males.

More in SciAm. The fact that these manly-mouse-man results were achieved from girly-vanilla-yogurt is not lost on me.

But I want to know is, how exactly does one go about weighing the mice's testicles? Your thoughts in the comments. (via Ed Yong)