A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the

biological sciences Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, origin, evolution, and distribution of ...

. It is the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word for "window", and is used in various fields to describe a pore in an

anatomical Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

structure.

Biological morphology

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

, fenestrae are found in

cancellous bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

s, particularly in the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. In

anatomy Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

, the

round window The round window is one of the two openings from the middle ear into the inner ear. It is sealed by the secondary tympanic membrane (round window membrane), which vibrates with opposite phase to vibrations entering the inner ear through the oval ...

and

oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a connective tissue membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicl ...

are also known as the ''fenestra rotunda'' and the ''fenestra ovalis''. In

microanatomy Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visi ...

, fenestrae are found in

endothelium The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the r ...

of fenestrated capillaries, enabling the rapid exchange of

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

s between the blood and surrounding tissue. The elastic layer of the

tunica intima The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (biology), tunica (layer) of an artery or vein. It is made up of one layer of endothelium, endothelial cells (and macrophages in areas of disturbed blood flo ...

is a fenestrated membrane. In

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

, a fenestration is a new opening made in a part of the body to enable drainage or access.

Plant biology and mycology

plant biology Botany, also called plant science, is the branch of natural science Natural science or empirical science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empiri ...

, the perforations in a

perforate leaf Perforate leaves, sometimes called fenestrate, occur naturally in some species of plants. Holes develop as a leaf grows. The size, shape, and quantity of holes in each leaf can vary greatly depending on the species and can even vary greatly withi ...

are also described as fenestrae, and the leaf is called a fenestrate leaf. The

leaf window Leaf window, also known as epidermal window, and fenestration, is a specialized leaf structure consisting of a translucent area through which light can enter the interior surfaces of the leaf where photosynthesis can occur. The translucent struct ...

is also known as a fenestra, and is a translucent structure that transmits light, as in ''

Fenestraria ''Fenestraria'' (known as babies' toes) is a (possibly monotypic) genus of succulent plants in the family Aizoaceae, native to the Namaqualand in Namibia. Description The only species currently recognised in this genus is ''Fenestraria rh ...

''. Examples of fenestrate structures in the fungal kingdom include the symmetrically arranged gaps in the indusium ("skirt") of the mushroom ''

Phallus duplicatus ''Phallus duplicatus'' (common name, netted stinkhorn or wood witch) is a species of fungus in the stinkhorn family. The bell-shaped to oval cap is green-brown and the cylindrical stalk is white. When mature, the cap becomes sticky with a slimy ...

'', and the

thallus Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

of the coral lichen ''

Pulchrocladia retipora ''Pulchrocladia retipora'', commonly known as the coral lichen, is a species of fruticose lichen in the family Cladoniaceae. Found predominantly in Australasia, its habitats range from the Australian Capital Territory to New Zealand's North a ...

''.

Zoology

zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...

, the trilobite ''

Fenestraspis ''Fenestraspis'' is an extinct genus of trilobite in the order Phacopida from the Upper Pragian and Lower Emsian. ''Fenestraspis'' is unusual because of the development of extensive fenestrae in the posterior part of the body and apparently ...

'' possessed extensive fenestrae in the posterior part of the body. In the

Paleognathae Palaeognathae (; ) is an infraclass of birds, called paleognaths or palaeognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Pala ...

, there is an ilio–ischiatic fenestra. Fenestrae are also used to distinguish the three types of

amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tet ...

References

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Palaeontology Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geo ...

, volume=52 , issue=4 , pages=933–949 , doi=10.1111/j.1475-4983.2009.00878.x , bibcode=2009Palgy..52..933H , doi-access=free {{cite book , last1=Krstić , first=Radivoj V. , title=Human Microscopic Anatomy: An Atlas for Students of Medicine and Biology , publisher=Springer Berlin Heidelberg , publication-place=Berlin, Heidelberg , year=1991 , isbn=978-3-662-02676-2 , oclc=851388484 , page=56 {{cite journal , last1=Stocker-Wörgötter , first1=Elfie , last2=Elix , first2=John A. , year=2006 , title=Morphogenetic strategies and induction of secondary metabolite biosynthesis in cultured lichen-forming Ascomycota, as exemplified by ''Cladia retipora'' (Labill.) Nyl. and ''Dactylina arctica'' (Richards) Nyl. , journal=Symbiosis , volume=40 , pages=9–20 , url=https://dalspace.library.dal.ca/bitstream/handle/10222/78197/VOLUME%2041-NUMBER%201-2006-PAGE%209.pdf?sequence=1 {{cite book , last1=Ulloa , first1=Miguel , last2=Halin , first2=Richard T. , title=Illustrated Dictionary of Mycology , edition=2nd , year=2012 , publisher=The American Phytopathological Society , location=St. Paul, Minnesota , isbn=978-0-89054-400-6 , page=220 Anatomy Angiology Fungal morphology and anatomy sv:Fenestrae