Antheridium

An antheridium is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm).

Antheridia are present in the gametophyte phase of cryptogams like bryophytes and ferns.

[2] Many algae and some fungi, for example, ascomycetes and water moulds, also have antheridia during their reproductive stages.

The female counterpart to the antheridium in cryptogams is the archegonium, and in flowering plants is the gynoecium.

The sterile cells may form a central support structure or surround the spermatogenous tissue as a protective jacket.

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.
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.
Micrograph of antheridium anatomy in Porella , a leafy liverwort