Rod-shaped accumulations in cisternae of the endoplasmic reticulum in root cells of Lepidium sativum seedlings.

Ultrathin sections through the median plane of norm al, 48-hrs-old seedling roots of cress, showed the presence of accumulations of a finely fibrillar material. These inclusions were confined to the cisternae of the granular endoplasmic reticulum of surface cell layers of the root tip and the root-hair zone. The rod-shaped structure and random orientation of these inclusions were clearly seen in 3-dimensional reconstructions of serial ultrathin sections.