If uninterrupted, growth in fungi proceeds radially
outwards from the initiating spore, allowing the fungal colony to colonise new
regions potentially rich in nutrients. Actual growth occurs solely at the
hyphal tip; as this happens, the terminal cell grows longer, until eventually a
new cross wall or septum is formed. Cells away from the tip do not become any
longer during hyphal extension, however hyphae in this region may develop into
aerial reproductive structures. Older hyphae at some distance from the tip may
become completely empty of cytoplasm.
Cell counts and turbidometric measurements are not
appropriate to estimate growth of fungi; however total mycelial mass can be
measured and its change plotted against time. A fungal growth cycle shows
roughly the same phases of growth as described above for bacteria.