Ultrastructural Observation and Cytochemical Analysis of Oogenesis in Marchantia polymorpha L. New Observations on the Morphology and Structure of Marchantia polymorpha Gametophores in Sexual Reproduction Adaption In vitro Propagation, Dedifferentiation and redifferentiation of Marchantia polymorpha L. Microstructural Observations and Cytochemical Studies on the Archegonial Development and Oogenesis of Marchantia polymorpha