A sac-like structure that is found in the mature gland[GO]. [ http://amigo.geneontology.org/amigo/term/GO:0060749 ]

Synonyms: mammary alveolus lactiferous alveolus lactiferous gland alveolus alveolus of lobe of breast alveolus of lobe of mammary gland lobe of breast alveolus lobe of mammary gland alveolus alveolus of lactiferous gland alveolus of mammary gland

This is just here as a test because I lose it