A filamentous structure, or trichome, is characterized by the presence of heterocysts and maintains a consistent diameter along its entire length. There is no branching of the trichome, and the heterocysts are either interspersed within the filament or situated at its base. These trichomes are enveloped in a nearly invisible mucous sheath, and the heterocysts are positioned between the cells. The filaments can exist as solitary entities or be clumped together within a gelatinous matrix.