In anatomy, a<unk> , or<unk> a, is a smooth<unk>  consisting of a thin layer of cells which excrete a fluid, known as<unk>  fluid.<unk> s line and enclose several body cavities, known as<unk>  cavities, where they secrete a lubricating fluid which reduces friction from muscle movement.<unk> a is not to be confused with adventitia, a connective tissue layer which binds together structures rather than reducing friction between them.
Serous membrane
Vesicle 
Cuticle
Basolateral membrane
Apical membrane
Nucleohyaloplasm
Germ layer
Adnexa