Lamella (cell biology)

A lamella (plural: "lamellae") in biology refers to a thin layer, membrane or plate of tissue.[1] This is a very broad definition, and can refer to many different structures. Any thin layer of organic tissue can be called a lamella and there is a wide array of functions an individual layer can serve. For example, an intercellular lipid lamella is formed when lamellar disks fuse together to form a lamellar sheet. It is believed that these disks are formed from vesicles, giving the lamellar sheet a lipid bilayer that plays a role in water diffusion.[2]

Another instance of cellular lamellae can be seen in chloroplasts. Thylakoid membranes are actually a system of lamellar membranes working together, and are differentiated into different lamellar domains. This lamellar system allows plants to convert light energy into chemical energy.[3] Chloroplasts are characterized by a system of membranes embedded in a hydrophobic proteinaceous matrix, or stroma. The basic unit of the membrane system is a flattened single vesicle called the thylakoid; thylakoids stack into grana. All the thylakoids of a granum are connected with each other, and the grana are connected by intergranal lamellae.[4]

It is placed between the two primary cell walls of two plant cells and made up of intracellular matrix. The lamella comprises a mixture of polygalacturons (D-galacturonic acid) and neutral carbohydrates. It is soluble in the pectinase enzyme.

Lamella, in cell biology, is also used to describe the leading edge of a motile cell, of which the lamellipodia is the most forward portion.[5]

The lipid bilayer core of biological membranes is also called lamellar phase.[6] Thus, each bilayer of multilamellar liposomes and wall of a unilamellar liposome is also referred to as a lamella.