They grow by extension of the terminal cell, which involves dissolution of the old and formation of a new wall, or septum.  
Electron dense spheres known as Woronin bodies sometimes block pores in the dividing walls of these structures.  They grow by extension of the terminal cell, which involves dissolution of the old and formation of a new wall, or septum.  They can specialize to form reproductive structures known as conidiophores, or aggregate to locate resources beyond a zone of depletion, forming rhizomorphs.  They can also invaginate plant cells in the form of haustoria, transferring organic carbon to the rest of the thallus.  FTP name these tubular structures that form a network known as the mycelium in many fungi.
Electron dense spheres known as Woronin bodies sometimes block pores in the dividing walls of these structures.  
hyphae (before "extension of the terminal cell," accept mycelium or mycelia and prompt on septum or septa)