What is the Difference Between Basal Lamina and Basement Membrane?

The basal lamina and basement membrane are both components of the extracellular matrix that support and provide structure to cells. However, there are some differences between the two:

1. Composition: The basal lamina is composed of two layers: the lamina lucida and lamina densa. The basement membrane, on the other hand, is composed of three layers: the lamina lucida, lamina densa, and lamina fibro-reticularis.
2. Visibility: The basal lamina is visible only through an electron microscope, while the basement membrane is visible under light microscopy.
3. Location: The basal lamina is located between the connective tissue and the basolateral side of a cell layer. The basement membrane is located between epithelial tissues (mesothelium and endothelium) and the underlying connective tissue.
4. Terminology: The term "basal lamina" is usually used with electron microscopy, while the term "basement membrane" is usually used with light microscopy.

In summary, the basal lamina is a layer of the extracellular matrix secreted by epithelial cells, while the basement membrane is a broader structure that includes the basal lamina and additional layers. The basal lamina is visible only through an electron microscope, whereas the basement membrane can be seen under light microscopy.

Comparative Table: Basal Lamina vs Basement Membrane

The basal lamina and basement membrane are both extracellular matrices found in epithelial tissues, but they have distinct compositions and functions. Here is a table summarizing their differences:

The basal lamina is composed of two layers and is secreted by epithelial cells, providing structural support and adhesion for those cells. The basement membrane, on the other hand, is composed of three layers and serves as a protective barrier between epithelial tissues and underlying connective tissues.