Ultrastructural Aspects of the Embryo Sac of Jasione Montana L.: Cell Walls

In the mature embryo sac of Jasione montana, Campanulaceae, the egg cell is surrounded by the synergids and the central cell and does not border the embryo sac wall. The strand-like filiform apparatus extends through the synergids up to the egg cell. The heavy cutinization of the synergid cell walls in the micropylar region seems to be unique to Jasione montana so far. In the median and chalazal part the distinct cuticle of the integumentary tapetum and the thin cuticle of the embryo sac separate both tissues. True cell walls are lacking inside the embryo sac except for the thick cutinized cell wall between the synergids at the micropylar end and the thin cell walls surrounding the antipodals. In the other regions the plasmalemmae face each other.