Differences in Fine Structures between Normal and RNA-induced Drosophila Pole Cells: (Drosophila pole cell/fine structure/polar granule/nuclear body/cytoplasmic determinant).

Fine structures were compared between normal pole cells and those induced in embryos that had been uv-irradiated and then injected with intact polar plasm or with poly(A) RNA extracted from cleavage embryos. Nuclei in nomal pole cells were spherical. In contrast, those in the induced pole cells were deformed to variable extents depending on materials injected with. Polar granules were smaller in pole cells induced by injection of poly(A) RNA than in normal pole cells. The size of polar granules in polar-plasm-induced pole cells was intermediate between those in poly(A) RNA-induced and normal pole cells. Small polar granules were observed in posterior cells of embryos uv-irradiated, nevertheless those cells were columnar and with identical morphology to somatic cells. Nuclear bodies showed a similar tendency in size differences as observed in polar granules in three types of pole cells observed.