aseptate

Aseptate refers to tissue, organisms, or structures that lack septa, the cross-walls that divide compartments. In mycology, aseptate hyphae are continuous tubes of cytoplasm that do not possess septa, a condition also called coenocytic. This organization results in a single multinucleate cell extending through the hypha.

Aseptate hyphae are characteristic of certain fungal lineages, notably the early-diverging zygomycetes, historically placed in Zygomycota, and some related groups. In these fungi, hyphae are typically broad and multinucleate, with cytoplasm streamed along the length of the filament. Other fungal groups possess septate hyphae, in which cross walls divide hyphae into individual cells.

In clinical mycology, nonseptate or aseptate hyphae are a diagnostic feature of mucormycosis-causing fungi (order Mucorales and related groups), where hyphae are broad, irregular, and branch at wide angles. However, classification based on septation is not always consistent with modern taxonomy, and some organisms may exhibit partial segmentation or septa in certain conditions.

The term can also apply to non-fungal contexts, such as tissues or organisms that lack internal partitions, though it is most commonly used to describe hyphal structure in fungi.