Hypha, an elongated cylindrical filamentous structure, either unsegmented (unicellular) or segmented (multicellular), branched or unbranched and increasing by apical growth, which occurs in some algae and most fungi. Whether segmented or not, a hypha generally contains many nuclei. Loops frequently unite distinct threads, and clamp-connections, by a protuberance extending backwards at a transverse wall and joining the next cell, also occur. Fungal mycelium or "spawn" commonly consists of much branched unsegmented hyphee; and the so-called "compound thallus" of the larger fungi is made up of numerous multicellular hyphee, either densely interwoven into a felt (tela contcxta) or parallel and firmly adherent. They then so resemble parenchymatous tissue, the result of cell-division, as to be called pseudo-parenchyma.