Argyrophilic nuclear structures in root apices

The general structure of the plant cell nucleus is quite well known at the level of resolution afforded by both the light and electron microscope [3]. Nuclei of root meristems, in particular, are favoured for structural studies since they are so readily available and because they are also so obviously active in the genetic and metabolic activities that result in mitosis, cell growth and cell differentiation. Micrographs showing the appearance of chromatin, nucleolus and nuclear envelope in meristematic cells are familiar illustrations in most books on plant cytology. However, patient searching of electron microscope sections, and the use of new cytochemical techniques, can reveal structures within the nucleus that are less familiar, and whose significance or function is unknown. The aim of this contribution is to draw attention to two unfamiliar nuclear components and to present data relating to their behaviour in different regions of the root apex.