From a ventral perspective, magnified 307X, this 2006 scanning electron microscopic (SEM) image depicted an enlarged view of the chitinous, exoskeletal surface of a female louse, Pediculus humanus var. corporis, in the region where the organism’s forelegs attached to its thoracic region. In this particular view, the exoskeleton seems to be composed of interlocking plates, in order to provide flexibility to the joint. Note how the chitinous components were arranged in a plate-like manner, attached to one another with thin, layers of exoskeletal chitin. Chitin is a molecule made up of bound units of acetylglucosamine, which is joined in such a way as to allow for increased points at which hydrogen bonding can occur. In this way chitin provides increased strength, and durability as an exoskeletal foundation.