Tendon cells form a connecting epithelial layer between the muscle and shell in molluscs.
In gastropods, for example, the retractor muscles connect to the shell via tendon cells.
Muscle cells are attached to the collagenous myo-tendon space via hemidesmosomes.
The myo-tendon space is then attached to the base of the tendon cells via basal hemidesmosomes, while apical hemidesmosomes, which sit atop microvilli, attach the tendon cells to a thin layer of collagen.
Dense bundles of microfilaments run the length of the cell connecting the basal to the apical hemidesmosomes.