Organellides

Organellide is a term used in some cell biology writings to describe small, organelle-like compartments within a cell that are not universally recognized as canonical organelles. The term combines organelle with the suffix -ide, signaling resemblance rather than identity. There is no single, standardized definition; usage varies by author. In some contexts, organellides are proposed to be transient, membrane-bound bodies derived from endomembrane compartments, while in others they are posited as relics of endosymbiotic events or as metabolically specialized micro-compartments.

Observationally, organellides are described in diverse eukaryotes including certain protists and algae, and occasionally in bacteria with complex cell architectures. They are typically described as bounded by a lipid membrane, lacking a complete genome, and enriched for particular enzymes or lipids, though these characterizations are not universal. Methodologically, detection relies on electron microscopy, immunolabeling of marker proteins, or dye-based probes; distinguishing genuine organellides from small vesicles, autophagosomes, or lysosome-related bodies remains challenging.

Taxonomically, organellide is not an official category; it functions as a descriptive label that may reflect hypotheses about subcellular organization or evolutionary processes. Critics warn that the term can be overly vague without clear criteria. Proponents argue that recognizing organellides could illuminate the pathways of organelle biogenesis, intracellular trafficking, and the evolution of cellular compartments, and may reveal intermediate states in organelle evolution.

Further research, standardized definitions, and comparative analyses across taxa are needed to determine whether organellides represent a distinct class of cellular structures or a placeholder for diverse vesicular bodies.