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week of each other—reported that, in reticulocytes, transferrin receptors associated with small 50 nM vesicles are literally jettisoned from maturing blood reticulocytes into the extracel-lular space. The name “exosome ” for these extracellular vesi-cles was coined a few years later by Rose Johnstone, although the term had in fact been used a few years earlier, when refer-ring to other membrane fragments isolated from biological fluids (Trams et al., 1981; the term “exosome complex ” has also been used for a totally different entity: namely, the intracellular parti-cle involved in RNA editing [Mitchell et al., 1997]). The promise of these early discoveries has been recognized over the inter-vening three decades by a nearly explosive growth in the field of exosome biology, resulting in the formation of various societies (International Society for Extracellular Vesicles and The Ameri-can Society for Exosomes and Microvesicles) and even a dedi-cated journal (Journal of Extracellular Vesicles), plus numerous international meetings and well over a thousand publications on exosomes, to date. In this comment, we describe how we dis-covered this new cellular pathway and provide our perspective on the major advances and future directions of this field. For a more detailed analysis of the state of the field and its future challenges, see Raposo and Stoorvogel (in this issue). Our investigations were initiated when one of us (C.V. Harding), then an MD/PhD student, embarked on a study of en-docytosis for his PhD thesis and exploited the expertise of two adjacent laboratories in the Department of Cell Biology an