Abstract
Following Kihara and Hirayoshi4) we have adopted the shrinkage of FAA-fixed microspores as a criterion of classifying the microspore stage. In the present study the possibility that the shrinkage was induced by the fixatives was examined by using three fixatives: acetic acid-alcohol (AA), formalin-acetic acid-alcohol (FAA) and glutaraldehyde (GA). AA and FAA shrank microspores remarkably, while GA did not. This result shows that shrunk configurations of microspores are artifacts induced by the fixatives (AA and FAA) and led us, to revise the terminology of classifying the microspore stage. Hereafter we divide the microspore stage according to the developments of both vacuolcs and exines into three phases (early microspore phase, middle microspore phase and late microspore phase) and divide the pollen stage according to the engorgement of reserve substances into two phases (vacuole pollen phase and engorged pollen phase).
