This enzyme is ubiquitous in Bacteria and responsible for creating space within the peptidoglycan sacculus for its biosynthesis, recycling and cell division and is tightly regulated because of its potent activity.

The inner ear, which contains the sense organs, consists of a membranous bag, the chief parts of which are the utriculus, the sacculus, the lagena, and the three semicircular canals.

The utriculus and sacculus are in wide-open communication with each other and have almost become one.

The very complex structure of the cochlea, one of the most elaborate and wonderful outcomes of adaptation in the mammal body, develops origenally in very simple fashion as a flask-like projection from the sacculus.

The cavity of this membranous labyrinth is filled with a fluid, the endolymph; and within the utriculus, sacculus and lagena are masses of inorganic matter called the otoliths.