Lamellar granule

Lamellar granule

Lamellar granules, also known as Odland bodies or membrane-coating granules, are secretory organelles found in the stratum granulosum layer of the epidermis. They are responsible for the delivery of lipids and proteins to the stratum corneum, the outermost layer of the epidermis, which plays a crucial role in the skin's barrier function.

Structure

Lamellar granules are small, oval-shaped organelles that are surrounded by a lipid bilayer. They contain a variety of lipids, including ceramides, cholesterol, and free fatty acids, as well as enzymes such as proteases and phospholipases. These components are packaged into the granules in the Golgi apparatus before being transported to the cell surface.

Function

The primary function of lamellar granules is to contribute to the formation of the skin's barrier. They do this by secreting their contents into the extracellular space of the stratum corneum. The lipids and proteins released from the granules form a waterproof seal that prevents the loss of water from the body and protects against the entry of harmful substances.

In addition to their role in barrier formation, lamellar granules also contribute to the process of desquamation, or skin shedding. The proteases they contain help to break down the connections between dead skin cells, allowing them to be shed from the surface of the skin.

Clinical significance

Defects in the function or formation of lamellar granules can lead to a variety of skin disorders. For example, mutations in the gene encoding the protein ABCA12 can disrupt the transport of lipids into lamellar granules, leading to the skin condition Harlequin ichthyosis. Similarly, a lack of the enzyme acid sphingomyelinase can impair the breakdown of lipids within lamellar granules, resulting in Niemann-Pick disease.

See also

• Epidermis (skin)
• Stratum corneum
• Stratum granulosum
• Harlequin ichthyosis
• Niemann-Pick disease