Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

The two Pulis Quastie and Gin-Gin run in the snow in their garden in Lautertal, southern Germany, Thursday, January 5, 2017. (Photo by Michael Probst/AP Photo)

A couple have taken their love of animals to the extreme – by opening up their home to over 100 rescued animals. Dr Prakash Amte and his wife, Dr. Mandakini Amte have dedicated their lives to helping both the animals – and people – of Hemalkasa, Maharashtra in India. Here: Prakash Amte is seen playing with a Hyena from his orphanage on September 19, 2017 in Maharashtra, India. (Photo by Haziq Qadri/Barcroft Media)

Dogs of a visitor pass by the grave of Marquise and Tony, the two small dogs of the Princess Lobanoff de Rostoff at the cimetiere des chiens (Cemetery of dogs) ahead of the commemoration of All Saints Day at the Montmartre cemetery in Asnieres, northern Paris, France, October 30, 2016. (Photo by Charles Platiau/Reuters)

A White Crested Poland is seen at the National Poultry Show on November 20, 2016 in Telford, England. The annual event continues to grow with around 7000 entries this year from all around the world. (Photo by Leon Neal/Getty Images)

Youth category winner: Symphony No 5 by Giacomo Redaelli (Italy). (Photo by Giacomo Redaelli/2019 Nature Photographer of the Year)

Arctic wolves in their new enclosure in the wildlife park in Hanau, Germany, 10 February 2015. The pack is one of the park's main attractions, which specializes in local and European breeds. (Photo by Boris Roessler/EPA)

A hot air balloon floats past an almost full rising moon on a warm fall evening near Encinitas, California October 5, 2014. (Photo by Mike Blake/Reuters)