<P> A hypha (plural hyphae, from Greek ὑφή, huphḗ, "web") 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 . </P> <P> A hypha consists of one or more cells surrounded by a tubular cell wall . In most fungi, hyphae are divided into cells by internal cross-walls called "septa" (singular septum). Septa are usually perforated by pores large enough for ribosomes, mitochondria and sometimes nuclei to flow between cells . The major structural polymer in fungal cell walls is typically chitin, in contrast to plants and oomycetes that have cellulosic cell walls . Some fungi have aseptate hyphae, meaning their hyphae are not partitioned by septa . </P>

In fungi the individual filaments of the body are called