Mesosome is known as a characteristic folded invagination of the cell membrane of bacteria which develops as an ingrowth. It is made up of tubules, vesicles and lamellae.
Mesosomes could be either lateral or septal.
Septal mesosomes connect plasma membranes to the nucleoid.
During the process of cell division, they also assist in septum formation and replication.
Lateral mesosomes are not connected to the nucleoid and comprise the respiratory enzymes and perform functions which are similar to that of eukaryotic mitochondria. However, they are called chondroid.
They are capable of increasing the enzymatic contact and surface area of the plasma membrane.