Breast tissue shown in pink and yellow
Alveoli (yellow) and contractile myoepithelial cells (pink) in human breast tissue
Caleb Dawson, courtesy of Nikon

The runner-up for the 2022 Nikon Small World Photomicrography Competition went to Caleb Dawson, a postdoc at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia. Dawson studies the mammary gland, and his image shows the mechanics of how milk is expressed from the breast. Milk is produced in the alveoli (yellow) and when it is feeding time, the cells marked in pink contract, squeezing the contents out into the milk ducts.