Clarification of the terminology of the major human salivary glands: Acinus and alveolus are not synonyms

Discrepancies in the terminology of the major human salivary glands often appear in anatomical textbooks and tend to adversely affect student's learning experience in Microscopic Anatomy. The main culprit is the inconsistent description of the morphology of these glands secretory end pieces where “acinus” and “alveolus” are used interchangeably. The correct terminology originated from Malpighi (1687), repeated by Kölliker (1854), but over the years has been misinterpreted by prominent authors as a result of the nature of specimen preparation. This commentary is based on etymology, current standard light microscopy, research studies and consultation with experts. The overall objective of this publication is to recommend that textbooks should endeavour to modify the relevant descriptions about this terminology in their future editions. The most appropriate terminology for the major human salivary glands would be: (1) the parotid gland, entirely serous, should be called compound acinar glands; (2) the submandibular glands are mixed glands; their serous components are compound acinar while some of the mucinous areas are tubular with serous, crescents or demilunes, as acinar end pieces hence they should be named compound tubuloacinar glands; (3) the sublingual glands, mainly mucous glands with tubular shape, with small acinar end pieces that are serous crescents thence they should be called compound tubuloacinar glands.