germ tube

A germ tube is an initial outgrowth from a fungal spore that develops into a hypha, which is a long, branching filament that forms the mycelium, the main body of a fungus. This process begins when a spore absorbs water, activating its cytoplasm and leading to nuclear division. A germ tube then emerges from the spore wall, enveloped by its own developing wall.1

Fungi reproduce both sexually and asexually. Asexual reproduction can occur through fragmentation of the mycelium, cell division (fission) in single-celled yeasts, or budding. In budding, a small outgrowth develops on the parent cell, receives a nucleus, and eventually detaches to form a new individual. For filamentous fungi, buds can act as spores, germinating to form new hyphae.2

Spores are typically single cells produced by fragmentation or within specialized structures. When conditions are favorable, these spores germinate and form germ tubes, initiating the growth of new fungal structures. A germ pore is a specific area on the spore wall through which the germ tube exits during germination.123