gametangia

Gametangia are reproductive organs in the gametophyte generation of many plants and algae. They enclose and protect developing gametes and are specialized for their production. The male gametangium, or antheridium, produces motile or non-motile sperm, depending on taxon; the female gametangium, or archegonium, produces and shelters the egg.

Antheridia are typically multicellular bodies with a jacket of protective cells; archegonia are flask-shaped structures with a ventral egg-containing chamber and a neck that leads to an opening.

In bryophytes and most ferns, the gametophyte is prominent and bears both antheridia and archegonia, often on separate structures. Fertilization requires water for sperm to swim from antheridia to archegonia; the zygote grows into a sporophyte that remains attached to the parental gametophyte.

In seed plants (gymnosperms and angiosperms), the gametophyte is reduced to microscopic structures inside the ovule or pollen; true antheridia and archegonia are largely absent; male gametophytes produce sperm via pollen grains, and female gametophytes produce eggs in embryo sacs; fertilization occurs through pollen tube growth.