<P> In bryophytes and other cryptogams sperm reach the archegonium by swimming in water films, whereas in Pinophyta and Angiosperms the pollen are delivered by wind or animal vectors and the sperm are delivered by means of a pollen tube . </P> <P> In the moss Physcomitrella patens, archegonia are not embedded but are located on top of the leafy gametophore (s . Figure). The Polycomb protein FIE is expressed in the unfertilized egg cell (right) as the blue colour after GUS staining reveals . Soon after fertilisation the FIE gene is inactivated (the blue colour is no longer visible, left) in the young embryo . </P> <P> They are much - reduced and embedded in the megagametophytes of gymnosperms . The term is not used for angiosperms or the gnetophytes Gnetum and Welwitschia because the megagametophyte is reduced to just a few cells, one of which differentiates into the egg cell . The function of surrounding the gamete is assumed in large part by diploid cells of the megasporangium (nucellus) inside the ovule . Gymnosperms have their archegonium formed after pollination inside female conifer cones (megastrobili). </P>

Where is the egg located in the archegonium