Para-crystalline membrane structures resembling prolamellar bodies in the invasion zones of indeterminate root nodules of Vicia faba L.

Novel para-crystalline structures resembling prolamellar bodies in etioplasts were found in the invasion zones of indeterminate root nodules of Vicia faba, which possess persistent meristems and exhibit sequential developmental stages. The para-crystalline structures existed in most cells in the area of the invasion zone and a hexagonal arrangement of tubular membranes was recognized. Extensive membranes, apparently procured from the structures, were often in contact with the bacteria in young infected cells. We propose that the para-crystalline structures serve as a reservoir of membranes for the formation of the numerous symbiosomes that propagate and fill the infected cells, and suggest naming them pro-symbiosome membrane bodies.