Mesosomallike

Mesosomallike describes cellular features in prokaryotes that resemble mesosomes—invaginations or vesicular compartments associated with the bacterial plasma membrane as observed in some electron micrographs. The term is used descriptively when structures appear similar to mesosomes but their identity and function are not established.

Historically, mesosomes were proposed as organelles involved in respiration, synthesis of cell wall components, or DNA replication and segregation. Subsequent work, however, has largely attributed many observed mesosomes to artifacts introduced during sample preparation, particularly chemical fixation and dehydration. As a result, the concept of a true, universal mesosomal organelle has fallen out of favor in contemporary microbiology, and mesosomallike descriptors are commonly used to note resemblance rather than confirmed function.

In practice, mesosomallike structures may arise from natural membrane invaginations under certain physiological conditions or during cell division, as well as from imaging artifacts. Their appearance is influenced by fixation methods, staining procedures, and the imaging modality used. Modern techniques such as cryo-electron microscopy and tomography can reduce fixation-induced distortions and help distinguish genuine membrane organization from artifacts.

Because mesosomes are not recognized as definitive, stable organelles in most bacteria, mesosomallike descriptions emphasize morphological similarity rather than implying a specific, conserved role. They are primarily used to characterize observed invaginations or vesicle-like features that resemble mesosomes in β-diversity experiments or historical literature. See also: Mesosome.