The lamina lucida is so named because of its translucent appearance on electron microscopy. In comparison, the lamina densa is an electron-dense region that lies just below the lamina lucida. The lamina lucida is composed of the transversing parts of the integrin and BP180 proteins. These two molecules attach to the laminin class of proteins in the lamina densa. The lamina lucida is considered to be the weakest part of the BMZ, and it is the blister plane in suction blisters, junctional epidermolysis bullosa, and salt-split skin. The lamina densa is composed of a latticework of type IV collagen. Type IV collagen is found only in the lamina densa. It is unique in that it retains its globular regions on either end. These form attachments to other type IV collagen molecules to create the lattice. Collagen type IV binds strongly to a dumbbell-shaped protein named nidogen. This nidogen protein is critical in attaching to the laminin proteins in the lamina densa. Nidogen locks the type IV collagen to the laminins, which are bound to the overlying integrin and BP180.
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