Do mast cells contribute to the continued survival of vertebrates?

This study is an attempt to shed light on why the connective tissue mast cell (MC) is preserved in all species with a blood circulatory system, i.e., the vertebrates since >500 million years, which suggests that the MC performs as yet not understood indispensible life‐promoting actions. The literature survey focuses on data in published papers on MC functions in immunological and nonimmunological reactions, host protection, pregnancy, inflammation, and wound healing. All data are thus accessible to the reader. The MC is a secretory cell with a unique mediator profile. A distinctive role for MCs is defined not only by their extensive mediator composition but also by their prominent ability to affect the vasculature to expedite selective cell recruitment and permeability changes and to set the stage for an appropriate acquired response. MCs, harboring a wide range of surface membrane receptors, are activated by the major female sex hormones as well as by diverse potentially adverse stimuli. MC activation/degranulation creates a presumably unique triad tissue response in physiological and pathological situations alike: extracellular matrix degradation and tissue remodeling, de novo cell proliferation, and de novo angiogenesis. As shown in the literature, MC‐activation is crucial for successful female reproduction in the mouse, implying one of possibly several yet unidentified physiological roles of MCs. Moreover, the activated MC aids newborns to survive to reproductive age owing to its key beneficial actions in inflammation and wound healing. Thus, a not previously described life‐perpetuating loop spanning generations are apparently formed, which, hypothetically, could contribute to the continued survival of the vertebrates.