Amphiphilic structures (vesicles, micelles, bilayers) are important in biological and chemical processes. The structural transition from micelles to vesicles through disk-like intermediate states has already been demonstrated. We disclose a new route for the micelle-vesicle transition, where micelles aggregate to first form long tubules that become unstable, and break up into vesicles. A simple theory, based on energy principles, is presented to attempt to explain the tubule-vesicle transition. Observation of this tubular intermediate state has been facilitated by the development of an integrated microfluidic chip/cryo-TEM unit. Although this transition has been observed in a specific amphiphilic system where micellar solutions of cetyl trimethyl ammonium bromide (CTAB) and dodecyl benzene sulfonic acid (HDBS) are mixed to form vesicles, this new tool can be applied quite broadly to study transient structures in nanoscale systems.