During the past three decades, histology has seen enormous progress, thanks to new techniques and new investigation instruments. Numerous discoveries of important structures and morphofunctional phenomena have been described in a wealth of papers of ever increasing size and complexity. These publi­ cations have become difficult to follow, not only because of their number, but also because of a disparity of terminology and the multitude of synonyms employed by different authors. All of this makes reading and comprehension of the progress that has been achieved laborious, even for histologists, but especially for students, researchers in other basic branches of medicine, or clinicians who have to consult histological texts during their studies or investigations. In order to facilitate the orientation of all those interested in histology, a concise and practical volume in encyclopedic style, defining and, at the same time, illustrating fundamental histolog­ ical terms, enumerating synonyms, and describing morpho­ functional phenomena has become necessary, both because a work of this genre does not exist and because the list of Latin terms elaborated by the International Anatomical Nomenclature Committee in 1977 does not give illustrations or definitions of histological terms. The present work attempts to redress this deficiency.