hypha

Hypha is a thread-like, elongated cell that constitutes the basic filamentous unit of most fungi. Collectively, many hyphae form the mycelium, the vegetative body responsible for growth and nutrient acquisition. Hyphae are typically tubular and highly extensible at their tips, enabling fungi to explore substrates.

Most fungi have hyphae divided into cells by cross walls called septa, with pores that allow cytoplasm and organelles to pass between compartments. Some groups, such as many zygomycetes and their relatives, have coenocytic hyphae that lack septa and contain many nuclei within a continuous cytoplasm. The cell wall of hyphae is primarily chitin and glucans, providing strength for growth under turgor pressure.

Growth occurs primarily at the apex, driven by vesicle delivery and cytoskeletal organization around a structure called the Spitzenkörper. Hyphae secrete enzymes into the environment to digest complex organic matter, creating an osmotic gradient that enables nutrient uptake along the length of the filament.

Hyphae serve vegetative and reproductive roles. Vegetative hyphae absorb nutrients; aerial hyphae can form reproductive structures that produce spores, enabling dispersal. Spore-forming strategies vary by lineage and include conidia on tips of specialized hyphae in Ascomycota and Eurotiomycetes, as well as basidiospores on basidiocarp structures in Basidiomycota.

In ecological terms, hyphae are central to decomposition, nutrient cycling, and symbiotic associations such as mycorrhizae. In humans, some fungi with invasive hyphae can cause infections, highlighting the medical relevance of their filamentous growth.