Mechanosensory cells in annelid oligochaete Lumbricus terrestris (Linnaeus, 1758): a new insight on worm evolution

Ciliated and non-ciliated mechanosensory cells in invertebrates have intricate cytoskeletal structures that, combined with microtubules, act as a mechanical link between external stimulus and signal processing. As a result, they can perceive forces like touch, cuticle deformation, gravity and sound. Through the expression of antibodies against serotonin (5-HT), calbindin, inducible nitric oxide synthase (iNOS) and α-smooth muscle actin (αSMA), this research aims to investigate mechanosensory cells in the integument of Lumbricus terrestris (Linnaeus, 1758) in an evolutionary perspective. In the epidermis, we discovered isolated mechanosensory cells that were immunopositive to every antibody examined. Our findings improve the knowledge and the evolution of annelid sensory biology adding new insights on the sensory signal transduction and help to better understand the morpho-structural adaptations of invertebrate skin on an evolutionary scale and to give more taxonomic data for species distinction.