antheridium

alt=Here is a diagram of antheridium structure in a liverwort, which is representative of most antheridia structures throughout species. It is a thin cellular layer that encapsulates many sperm cells.|thumb|General structure of antheridia. Antheridia consist of a thin cellular layer that holds many sperm inside. Here, the diagram of a liverwort antheridium is shown.

An antheridium is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium.