What is the reproductive structure in some fungi formed by the union of isogametes?

The reproductive structure formed by the union of isogametes in some fungi is known as a zygospore. In fungi, isogametes are gametes that are morphologically similar, meaning they do not have distinct male and female forms. When two of these gametes unite, they can fuse to form a diploid zygote, and this zygote develops into a zygospore.

Zygospores serve as a resting or survival structure, capable of enduring unfavorable environmental conditions until conditions improve for growth and reproduction. This structure undergoes meiosis to produce haploid spores, which can then germinate and grow into new fungal organisms.

Other structures mentioned are associated with different reproductive strategies. An oogonium is the female reproductive structure that produces large, non-motile eggs in certain fungi. An antheridium is the male reproductive structure that produces sperm cells in those same organisms. A zoospore is a motile spore that can swim and is typically produced asexually; it does not involve the fusion of gametes. Thus, the zygospore is distinct for its formation from isogametes, emphasizing its role in the sexual reproduction of fungi.