* The female gametangium of the gametophyte, containing a basal egg cell and surrounded by an outer layer of sterile cells, the archegonial wall, which differentiates into a basal venter and proximal neck. | * The female gametangium of the gametophyte, containing a basal egg cell and surrounded by an outer layer of sterile cells, the archegonial wall, which differentiates into a basal venter and proximal neck. |