Asexual Sporulation in the Zygomycota

  • Fungi belonging to this group produce non-motile sporangiospores called APLANOSPORES within SPORANGIA - these are the result of cleavage of the sporangium protoplasm aound one or more nulcei.
  • Each uninucleate or multinucleate (depending on the species) portion of protoplasm becomes enclosed by a rigid wall and matures into an aplanospore.
  • Eventually, the sporangium wall bursts to liberate the spores, which are dispersed by air currents. A fragment of the sporangium wall (COLLARETTE) may remain.
  • An example is Mucor.
  • In some species the sporangium contains a COLUMELLA. This is a curved cross-wall (septum) which bulges into the sporangium, providing a larger surface area than a normal flat septum - this facilitates increased diffusion of nutrients to the developing spores within the sporangium, which is particularly important in larger sporangia.
Photomicrograph illustrating asexual sporulation in Absidia. - CLICK TO VIEW SPORANGIUM OF ABSIDIA - 34KB.
Diagram illustrating asexual sporulation in Zygomycota.

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