Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)

Actress/Singer Victoria Justice arrives at the 2012 Teen Choice Awards at Gibson Amphitheatre on July 22, 2012 in Universal City, California. (Photo by Jeffrey Mayer)

Manchester and Salford University students have been celebrate the last day of freshers week in Manchester, England on September 25, 2016. (Photo by Jordan Sinclair/UK News Pictures)

An instructor (C) adjusts the posture of students of flight attendant major during a training session at Anhui Foreign Languages University, in Hefei, Anhui province, China, May 25, 2015. (Photo by Reuters/China Daily)

Couples take part in a competition during a mass wedding of 64 doctoral student couples at Harbin Institute of Technology, a university in Harbin, Heilongjiang province, China, June 4, 2017. (Photo by Reuters/Stringer)

Participants dressed in Heroic Fantasy costumes pose for a picture as they wait backstage during the first edition of the HeroFestival in Marseille, November 9, 2014. The festival is dedicated to American superhero comics, Japanese mangas, Heroic Fantasy characters and video games universes. (Photo by Jean-Paul Pelissier/Reuters)

Pope Francis passes past a portrait of himself as he arrives to meet youths in Santo Tomas University in Manila, Philippines, Sunday, January 18, 2015. Francis is in the Philippines on Sunday, the final full day of a weeklong trip that also took him to Sri Lanka. (Photo by Alessandra Tarantino/AP Photo)

Wildlife photographer Danté Fenolio has headed into areas untouched by sunlight – deep seas, caves and underground – and found creatures that are exploding with colour. Here: The golden harlequin toad has vanished from the wild, and only a small number live on in captivity. A fungus caused them, and many other amphibians, to die out in their home in Central America. (Photo by Danté Fenolio/The Guardian/Johns Hopkins University Press)