Basal lamina

Basal Lamina

The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, although it does form a portion of the basement membrane in many tissues.

Structure

The basal lamina is composed of two layers, the clear layer and the dense layer. The clear layer is adjacent to the epithelial cells and is also known as the lamina lucida, while the dense layer is also known as the lamina densa due to its dense appearance on electron microscopy.

Function

The basal lamina serves several important functions in the body. It provides physical support for the epithelial cells, separating them from underlying connective tissue. It also acts as a barrier, preventing the passage of large molecules and cells between the epithelium and the underlying tissue. In addition, the basal lamina plays a role in cell differentiation, cell proliferation, and tissue repair.

Clinical significance

Abnormalities in the basal lamina can lead to a variety of medical conditions. For example, mutations in the genes encoding for basal lamina components can cause Alport syndrome, a genetic disorder characterized by kidney disease, hearing loss, and eye abnormalities. In addition, damage to the basal lamina can contribute to the development of cancer, as it can allow cancer cells to invade surrounding tissues.

See also

• Epithelium
• Extracellular matrix
• Basement membrane