Tratado Micrográfico de las Escamas Placoideas de ciertos Elasmobranquios
(Micrographic Treatise on the Placoid Scales of certain Elasmobrachii)
by Cato, 2011

This little booklet shows illustrations of microscopic placoid scales from twelve different shark species. The images are generated from a single shark scale.

The Placoid Scales, also known as dermic denticles, are modified teeth covered with a hard layer of enamel that protect the skin of Elasmobranchs. Like teeth, they grow from an inner core of pulp (formed by connective tissues, blood vessels and nerves) that is then covered with vitro-dentine.
One of the main characteristics of Placoid Scales is that, unlike bony fishes' scales, they do not increase in size as the fish grows.