Small fluid-filled sac, bladder-like structure, or blister.
Note: This term may refer to an anatomic structure, a subcellular organelle, or a liposome-related particle.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 820 (https://doi.org/10.1515/pac-2015-1202)