Lamina lucida

Lamina Lucida is a layer of the basement membrane zone that lies immediately beneath the epidermis. It is a clear layer, hence the name 'lucida', which means 'light' or 'clear' in Latin. The lamina lucida is part of the dermoepidermal junction, which is a complex structure that connects the outer epidermis and the underlying dermis.

Structure

The lamina lucida is a thin, electron-lucent zone that separates the epidermis from the lamina densa. It is approximately 40-70 nanometers thick. The lamina lucida is not always visible in electron microscopy, and its visibility can depend on the method of sample preparation. It is composed of extracellular matrix components, including laminin, nidogen, and collagen type IV.

Function

The primary function of the lamina lucida is to provide a barrier between the epidermis and the dermis. It also plays a role in cell adhesion, as it contains hemidesmosomes that anchor the epidermis to the basement membrane. The lamina lucida also contributes to the mechanical resistance of the skin.

Clinical significance

Alterations in the structure or function of the lamina lucida can lead to various skin diseases. For example, in bullous pemphigoid, an autoimmune blistering disease, antibodies target proteins in the hemidesmosomes, leading to separation of the epidermis from the basement membrane at the level of the lamina lucida. This results in the formation of blisters.

See also

• Basement membrane
• Epidermis (skin)
• Dermis
• Bullous pemphigoid