  The origin and early evolution of eukaryotes are one of the major transitions
in the evolution of life on earth. One of its most interesting aspects is the
emergence of cellular organelles, their dynamics, their functions, and their
divergence. Cell compartmentalization and architecture in prokaryotes is a less
understood complex property. In eukaryotes it is related to cell size, specific
genomic architecture, evolution of cell cycles, biogenesis of membranes and
endosymbiotic processes. Explaining cell evolution through form and function
demands an interdisciplinary approach focused on microbial diversity,
phylogenetic and functional cell biology. Two centuries of views on eukaryotic
origin have completed the disciplinary tools necessarily to answer these
questions. We have moved from Haeckel SCALA NATURAE to the un-rooted tree of
life. However, the major relations among cell domains are still elusive and
keep the nature of eukaryotic ancestor enigmatic. Here we present a review on
state of art views of eukaryogenesis; the background and perspectives of
different disciplines involved in this topic
