![Conidium](https://upload.wikimedia.org/wikipedia/commons/1/12/Conidium.png)
A hypha (; ) is a long, branching, filamentous structure of a
fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...
,
oomycete
Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...
, or
actinobacterium
The ''Actinomycetota'' (or ''Actinobacteria'') are a phylum of all gram-positive bacteria. They can be terrestrial or aquatic. They are of great economic importance to humans because agriculture and forests depend on their contributions to so ...
.
In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a
mycelium
Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrate (biology), substrates. A typical single ...
.
Structure
A hypha consists of one or more
cell
Cell most often refers to:
* Cell (biology), the functional basic unit of life
Cell may also refer to:
Locations
* Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...
s surrounded by a tubular
cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
. In most fungi, hyphae are divided into cells by internal cross-walls called "septa" (singular
septum
In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate.
Examples
Human anatomy
* Interatri ...
). Septa are usually perforated by pores large enough for
ribosome
Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to ...
s,
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
, and sometimes
nuclei to flow between cells. The major structural polymer in fungal cell walls is typically
chitin
Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
, in contrast to plants and oomycetes that have
cellulosic
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
cell walls. Some fungi have aseptate hyphae, meaning their hyphae are not partitioned by septa.
Hyphae have an average diameter of 4–6
µm.
Growth
Hyphae grow at their tips. During tip growth, cell walls are extended by the external assembly and
polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are ...
of cell wall components, and the internal production of new cell membrane.
The
Spitzenkörper
The Spitzenkörper (German for pointed body, SPK) is a structure found in fungal hyphae that is the organizing center for hyphal growth and morphogenesis. It consists of many small vesicles and is present in growing hyphal tips, during spore ger ...
is an intracellular organelle associated with tip growth. It is composed of an aggregation of membrane-bound vesicles containing cell wall components. The Spitzenkörper is part of the
endomembrane system
The endomembrane system is composed of the different membranes (endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes ...
of fungi, holding and releasing
vesicle
Vesicle may refer to:
; In cellular biology or chemistry
* Vesicle (biology and chemistry)
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form nat ...
s it receives from the
Golgi apparatus
The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ins ...
. These vesicles travel to the cell membrane via the
cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compos ...
and release their contents (including various cysteine-rich proteins including
cerato-platanin
In molecular biology, the cerato-platanin family of proteins includes the phytotoxin cerato-platanin (CP) produced by the Ascomycete ''Ceratocystis platani''. CP homologs are also found in both the Ascomycota and the Basidiomycota branches of Di ...
s and
hydrophobin
Hydrophobins are a group of small (~100 amino acids) cysteine-rich proteins that are expressed only by filamentous fungi that are lichenized or not. They are known for their ability to form a hydrophobic (water-repellent) coating on the surface ...
s) outside the cell by the process of
exocytosis
Exocytosis () is a form of active transport and bulk transport in which a cell transports molecules (e.g., neurotransmitters and proteins) out of the cell ('' exo-'' + ''cytosis''). As an active transport mechanism, exocytosis requires the use o ...
, where they can then be transported to where they are needed. Vesicle membranes contribute to growth of the cell membrane while their contents form new cell wall. The Spitzenkörper moves along the
apex
The apex is the highest point of something. The word may also refer to:
Arts and media Fictional entities
* Apex (comics), a teenaged super villainess in the Marvel Universe
* Ape-X, a super-intelligent ape in the Squadron Supreme universe
*Apex, ...
of the hyphal strand and generates apical growth and branching; the apical growth rate of the hyphal strand parallels and is regulated by the movement of the Spitzenkörper.
As a hypha extends,
septa
The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...
may be formed behind the growing tip to partition each hypha into individual cells. Hyphae can branch through the bifurcation of a growing tip, or by the emergence of a new tip from an established hypha.
Behavior
The direction of hyphal growth can be controlled by environmental stimuli, such as the application of an electric field. Hyphae can also sense reproductive units from some distance, and grow towards them. Hyphae can weave through a permeable surface to penetrate it.
Modifications
Hyphae may be modified in many different ways to serve specific functions. Some
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
fungi form
haustoria
In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates t ...
that function in absorption within the host cells. The
arbuscules of
mutualistic mycorrhiza
A mycorrhiza (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant ...
l fungi serve a similar function in nutrient exchange, so are important in assisting nutrient and water absorption by plants.
Ectomycorrhizal extramatrical mycelium
Ectomycorrhizal extramatrical mycelium (also known as extraradical mycelium) is the collection of filamentous fungal hyphae emanating from ectomycorrhizas. It may be composed of fine, hydrophilic hypha which branches frequently to explore and expl ...
greatly increases the soil area available for exploitation by plant hosts by funneling water and nutrients to
ectomycorrhizas
An ectomycorrhiza (from Greek ἐκτός ', "outside", μύκης ', "fungus", and ῥίζα ', "root"; pl. ectomycorrhizas or ectomycorrhizae, abbreviated EcM) is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobi ...
, complex fungal organs on the tips of plant roots. Hyphae are found enveloping the
gonidia A gonidium (plural gonidia) is an asexual reproductive cell or group of cells, especially in alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping t ...
in
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.[Mycelial cord
Mycelial cords are linear aggregations of parallel-oriented hyphae. The mature cords are composed of wide, empty vessel hyphae surrounded by narrower sheathing hyphae. Cords may look similar to plant roots, and also frequently have similar function ...]
s can be formed to transfer nutrients over larger distances. Bulk fungal tissues, cords, and membranes, such as those of mushrooms and
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.[felted
A felted material is a hairy or filamentous (hairy-like) fibre that is densely packed or tangled, forming felt or felt-like structures.
Anatomy and zoology
The dermis is described in Gray's Anatomy as "felted connective tissue, with a varyi ...]
and often
anastomosed hyphae.
Types
Classification based on cell division
*Septate (with septa)
**''
Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
''
and many other species have septate hyphae.
*Aseptate or
coenocytic
A coenocyte () is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes insid ...
(without septa)
**Non-septate hyphae are associated with ''
Mucor
''Mucor'' is a microbial genus of approximately 40 species of molds in the family Mucoraceae. Species are commonly found in soil, digestive systems, plant surfaces, some cheeses like Tomme de Savoie, rotten vegetable matter and iron oxide re ...
'',
some
zygomycetes
Zygomycota, or zygote fungi, is a former phylum, division or phylum of the kingdom Fungi. The members are now part of two Phylum, phyla: the Mucoromycota and Zoopagomycotina, Zoopagomycota. Approximately 1060 species are known. They are mostly t ...
, and other fungi.
*"Pseudohyphae" are distinguished from true hyphae by their method of growth, relative frailty and lack of
cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
ic connection between the cells.
** Yeasts form pseudohyphae.
They are the result of a sort of incomplete
budding
Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is know ...
where the cells elongate but remain attached after division. Some yeasts can also form true septate hyphae.
Classification based on cell wall and overall form
Characteristics of hyphae can be important in fungal classification. In
basidiomycete
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
taxonomy, hyphae that comprise the
fruiting body
The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cy ...
can be identified as generative, skeletal, or binding hyphae.
*Generative hyphae are relatively undifferentiated and can develop reproductive structures. They are typically thin-walled, occasionally developing slightly thickened walls, usually have frequent septa, and may or may not have
clamp connection
A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of Basidiomycetes fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rec ...
s. They may be embedded in mucilage or gelatinized materials.
*Skeletal hyphae are of two basic types. The classical form is thick-walled and very long in comparison to the frequently septate generative hyphae, which are unbranched or rarely branched, with little cell content. They have few septa and lack clamp connections. Fusiform skeletal hyphae are the second form of skeletal hyphae. Unlike typical skeletal hyphae these are swollen centrally and often exceedingly broad, hence giving the hypha a
fusiform
Fusiform means having a spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape, but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a b ...
shape.
*Binding hyphae are thick-walled and frequent branched. Often they resemble deer antlers or defoliated trees because of the many tapering branches.
Based on the generative, skeletal and binding hyphal types, in 1932
E. J. H. Corner
Edred John Henry Corner FRS (12 January 1906 – 14 September 1996) was an English mycologist and botanist who occupied the posts of assistant director at the Singapore Botanic Gardens (1929–1946) and Professor of Tropical Botany at the Uni ...
applied the terms monomitic, dimitic, and trimitic to hyphal systems, in order to improve the classification of
polypore
Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside (see Delimitation for exceptions). They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all polyp ...
s.
*Every fungus must contain generative hyphae. A fungus which only contains this type, as do fleshy mushrooms such as
agaric
An agaric () is a type of fungus fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. In the UK, agarics are called "mushrooms ...
s, is referred to as monomitic.
*Skeletal and binding hyphae give leathery and woody fungi such as
polypore
Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside (see Delimitation for exceptions). They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all polyp ...
s their tough consistency. If a fungus contains all three types (example: ''
Trametes
''Trametes'' is a genus of fungi that is distinguished by a pileate basidiocarp, di- to trimitic hyphal systems, smooth non-dextrinoid spores, and a hymenium usually without true hymenial cystidia.Ryvarden L. (1991). "Genera of polypores: Nomenc ...
''), it is called trimitic.
*If a fungus contains generative hyphae and just one of the other two types, it is called dimitic. In fact dimitic fungi almost always contain generative and skeletal hyphae; there is one exceptional genus, ''
Laetiporus
''Laetiporus'' is a genus of edible mushrooms found throughout much of the world. Some species, especially ''Laetiporus sulphureus'', are commonly known as sulphur shelf, chicken of the woods, the chicken mushroom, or the chicken fungus because ...
'' that includes only generative and binding hyphae.
Fungi that form
fusiform
Fusiform means having a spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape, but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a b ...
skeletal hyphae bound by generative hyphae are said to have sarcodimitic hyphal systems. A few fungi form fusiform skeletal hyphae, generative hyphae, and binding hyphae, and these are said to have sarcotrimitic hyphal systems. These terms were introduced as a later refinement by E. J. H. Corner in 1966.
Classification based on refractive appearance
Hyphae are described as "gloeoplerous" ("gloeohyphae") if their high refractive index gives them an oily or granular appearance under the microscope. These cells may be yellowish or clear (
hyaline). They can sometimes selectively be coloured by sulphovanillin or other reagents. The specialized cells termed
cystidia
A cystidium (plural cystidia) is a relatively large cell found on the sporocarp of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia. Since cystidia have highly varied and distinct shapes that ar ...
can also be gloeoplerous.
Classification based on growth location
Hyphae might be categorized as 'vegetative' or 'aerial.' Aerial hyphae of fungi produce asexual reproductive spores.
See also
*
*
*
References
External links
* Close-u
light micrographof coenocytic hyphae
movies by P.C. Hickey and N. Read, University of Edinburgh
Fungi Online: An Introduction to the Biology of Fungi
{{Fungus structure
Fungal morphology and anatomy