Dermatan sulphate - a glycosaminoglycan found in skin, tendon, blood vessel and heart valves.

    Desmosomes -one of the types of cell junctions by which cells join or communicate with each other. Desmosomes consist of a round plaque of protein, desmoplakin on the cell membrane. Into the plaque are attached fine filamanents which are part of the cell's cytoskeleton. So the plaque is attached to the skeleton of the cell. Where the filaments enter the plaque the are so dense as to be visible with a light microscope. They are then called tonofilaments. The plaque of one cell adheres to the plaque of another. This system of joining cells is designed to resist mechanical separation, so we see desmosomes joining epithelial cells which hold tightly to each other. If epithelium is processed for histology, some shrinkage occurs and the epithelial cells separate from each other, except where the desmosomes hold them together. The pulled out tags of cell membrane give these cells a star-like shape, and so they are called the stellate cells.

    Desquamation - the detachment of cells from the surface of an epithelium.

    Dextrans - polysaccharides made by bacteria. They have a slimy consistency and contribute to the sticky nature of plaque.

    Differentiate - change in the pattern of genes expressed by a cell resulting in altered function, from a more primitive parent cell to a more specialised group of daughter cells.

    Diphyodont - only two sets of teeth, one deciduous and one permanent (from "di" = two,"phyo+ = generation and "dont" =teeth). See also polyphyodont

    Displacement - of a tooth refers to its movement within the confines of the tooth socket. A tooth can be displaced more easily when forced in a lateral direction than when forced into the socket. Continual or frequent displacement of a tooth may lead to it repositioning itself in the socket.

    DNA - Deoxyribosenucleic acid - a complex nucleic acid molecule which is used by cells to store genetic material as genes which control the structure of proteins and hence influencing all enzyme reactions. DNA is coiled in a single closed loop in procaryotes, but coiled round other proteins to form a chromosome, and stored in the nucleus of eucaryotes

    Duct - a tube which carries a secretion onto the surface of skin or mucosa.