Nucleus and endoplasmic reticulum in differentiating root protophloem of Nicotiana tabacum.

@article{Esau1972NucleusAE,
  title={Nucleus and endoplasmic reticulum in differentiating root protophloem of Nicotiana tabacum.},
  author={Katherine Esau and Robert H. Gill},
  journal={Journal of ultrastructure research},
  year={1972},
  volume={41 1},
  pages={
          160-75
        }
}
In protophloem sieve elements of roots of Nicotiana tabacum L., nuclei disintegrate completely during cell differentiation. While the sieve element still hardly differs from meristematic cells next to it, the nucleus shows indications of reduction in the amount of chromatin, and its nucleolus is small. After the contents of the nucleus are more or less completely eliminated, the nuclear envelope partly collapses. Its integrity breaks down and the nuclear space is invaded by cytoplasmic… CONTINUE READING