fenestrate

Fenestrate is an adjective meaning having openings or fenestrae; the term derives from the Latin fenestra, meaning window. In biology, fenestrate describes tissues or vessels that possess small pores or openings. The most common usage refers to fenestrated capillaries, a type of blood vessel whose endothelium contains pores (fenestrae) that permit rapid exchange of substances between blood and surrounding tissue. Fenestrated capillaries occur in organs that require high permeability, such as the kidneys’ glomeruli, the endocrine glands, the intestinal mucosa, and the choroid plexus of the brain. Some fenestrated capillaries have diaphragms spanning the pores, which can regulate permeability, while others are freely permeable.

In botany, fenestrate or fenestrated may describe leaves with one or more holes or transparent patches, a condition seen in several plant species such as Monstera, which develop leaf fenestrations during maturation.

In architecture and design, fenestration refers to the arrangement, number, size, and proportion of windows and other openings in a building. Fenestrate as a verb means to furnish a wall or structure with windows or to form openings in it. The term is commonly used in architecture to discuss façade composition, light admission, and ventilation, as well as in restoration and conservation work.

The term is also used in paleontology and zoology to describe organisms or structures that show openings or perforations, though this usage is less common than the biological and architectural senses.