The Spitzenkörper (

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

for pointed body, SPK) is a structure found in fungal

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

that is the organizing center for hyphal growth and morphogenesis. It consists of many small

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like features o ...

and is present in growing hyphal tips, during spore

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fe ...

, and where branch formation occurs. Its position in the hyphal tip correlates with the direction of hyphal growth. The Spitzenkörper is a part of the endomembrane system in fungi. The vesicles are organized around a central area that contains a dense meshwork of

microfilament Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other pr ...

s. Polysomes are often found closely to the posterior boundary of the Spitzenkörper core within the ''

Ascomycota Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

'',

microtubules Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 a ...

extend into and often through the Spitzenkörper and within the Ascomycota Woronin bodies are found in the apical region near the Spitzenkörper. The

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. ...

of the extreme apex is occupied almost exclusively by secretory vesicles. In the higher fungi (

and

Basidiomycota 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, Bas ...

), secretory vesicles are arranged into a dense, spherical aggregation called the Spitzenkörper or ‘apical body’. The Spitzenkörper may be seen in growing hyphae even with a light microscope. Hyphae of the

Oomycota 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 ...

and some lower Eumycota (notably the

Zygomycota Zygomycota, or zygote fungi, is a former division or phylum of the kingdom Fungi. The members are now part of two phyla: the Mucoromycota and Zoopagomycota. Approximately 1060 species are known. They are mostly terrestrial in habitat, living ...

) do not contain a recognizable Spitzenkörper, and the vesicles are instead distributed more loosely often in a crescent-shaped arrangement beneath the apical

plasma membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

. This structure is most commonly found in

Dikarya Dikarya is a subkingdom of Fungi that includes the divisions Ascomycota and Basidiomycota, both of which in general produce dikaryons, may be filamentous or unicellular, but are always without flagella. The Dikarya are most of the so-called " ...

and was at first thought to only occur among them. . Vargas et al 1993 however were the first to find a Spitzenkörper in another clade, specifically the Allomyces ( Blastocladiomycota), then subsequently '' Basidiobolus ranarum'' which has been placed in several different phyla was also found to have an SPK. these and the

Blastocladiella ''Blastocladiella'' is a genus of fungus. Species * '' Blastocladiella anabaenae'' * '' Blastocladiella asperosperma'' * '' Blastocladiella britannica'' * '' Blastocladiella colombiensis'' * '' Blastocladiella cystogena'' * '' Blastocladiella ...

(also in Blastocladiomycota) are the only known taxa to bear this structure.

References

Cell biology Fungal morphology and anatomy Articles containing video clips {{mycology-stub