The r�le of membrane-bound cytoplasmic inclusions during gametogenesis in Lilium longiflorum thunb.

Abstract

In the prophase of both mega- and microsporogenesis, a sizeable proportion of the meiocyte cytoplasm becomes invested in double or multiple membrane-bround inclusions. This cytoplasm remains thus isolated from the rest of the cell until the completion of meiosis II in the female cells, or the 'young spore' stage in those of the male. Significantly this encapsulation proceeds immediately the elimination of the major part of the ribosome population from the cytoplasm and, further, the electron microscope reveals that those ribosomes contained in these membranous inclusions remain unaffected by the lytic enzymes active elsewhere in the cytoplasm at this time. This encapsulated cytoplasm is proposed to fulfill two rôles; one, that it carries reserves necessary for postmeiotic development through from the diplophase to the haplophase environment and, two, that it permits the continuity of protein synthesis throughout meiosis I and II, a period when the major part of the protein synthetic apparatus is absent.