Nucleo-Cytoplasmic Interaction following Meiosis in the Young Microspores of Lilium Longiflorum; Events at the Nuclear Envelope

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Abstract
Interaction between the nucleus and the cytoplasm of young microspores of Lilium longiflorum has been investigated during the tetrad and prevacuolate stages of microsporogenesis. Two types of membrane-bound inclusions become associated with the nucleus over this period, small vesicles invested by a single unit membrane profile and larger bodies, about 0.5 μm in diameter, with a double bounding membrane. The small vesicles contain an evenly staining matrix and are probably released from the perinuclear space into the cytoplasm, but the nature and fate of the larger bodies, which contain a granular matrix resembling nucleoprotein, is not evident. Their content suggests that they are formed in the nucleus but their strong similarity to double membraned inclusions, present in the cells since the mid-prophase stage, calls for an alternative interpretation. Ribbons or sheets of membrane, resembling elements of the ‘annulate lamellae’ characteristic of certain animal cells, are formed at the nuclear envelope in the late tetrad stage. The possibility that these events play an important part in the reorganisation of the cytoplasm for gametophyte growth is discussed.