title: Tubular elements in plastids in the female gamete of a fern, Pteris ensiformis.
abstract: Highly dedifferentiated plastids in the egg cells of the fern Pteris ensiformis contain tubules with an external diameter of about 36 nm and an internal of 12 nm. The tubules are unlike those described from other eukaryotic plastids, but, although larger, have some resemblance to the rhapidosomes of blue-green algae.
mesh_terms: D002736:Chloroplasts / Q000648:ultrastructure; D005260:Female; D008854:Microscopy, Electron; D010063:Ovum / Q000648:ultrastructure; D010944:Plants / Q000648:ultrastructure*