Art of Science_In Bloom (IMAGE) Walter and Eliza Hall Institute Caption In response to hormones released during lactation, the ducts and lobules of breast tissue ‘bloom’ to form clusters of alveoli. These contain milk-producing cells encircled by tiny muscle-like cells, which contract to deliver milk to an infant. Credit WEHI Usage Restrictions Free to share, must credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.