A comparison of autogenous theories for the origin of eukaryotic cells.

Abstract in brief

• Eukaryotic cells have unique features that evolved over time, and there are two main theories about their origin: nuclear endosymbiotic theories, which suggest that nuclei, cytoplasm, and mitochondria came together from different prokaryotes, and autogenous models, which propose that these structures formed within a single prokaryotic lineage.
• Recent autogenous models have shifted from the traditional outside-in (OI) approach, where the nuclear envelope formed from internal vesicles, to an inside-out (IO) model, which views the nucleus as originating from the original cell body with cytoplasm formed from extracellular protrusions; both models are compatible with different timing hypotheses about mitochondrial integration.
• The review highlights that features of eukaryotic cells align well with the inside-out model, but the debate continues, especially regarding whether phagocytosis (needed for mitochondria acquisition in some models) evolved before or after mitochondria, emphasizing the need for further research into the evolutionary relationships of mitochondria.