The archegonium is the female sex organ in bryophyte. It’s a flask shaped structure having three parts, namely
The short basal portion called the stalk,
The swollen middle portion called venter,
The tubular terminal portion called neck. The venter encloses a single egg and venter canal cell. When the archegonium ripens the egg undergoes maturation the venter canal cell and neck canal cell disintegrate. It results in the formation of a passage for the entry of sperms for fertilization.