The organization of cytoplasm in differentiating xylem

Abstract

A survey of the cytoplasmic organization of differentiating tracheids and ray parenchyma of Pinus radiata has been made. In these cells, which possess relatively thick lameilated and layered walls, the cytoplasmic organelles do not differ from those already described in other tissues. The shape of the organelles appears to some degree to reflect the degree of vacuolation of the cells. In highly vacuolate cells the endoplasmic reticulum tends to become aligned parallel to the cell surface. There was no evidence of penetration of the wall by any component of the cytoplasm other than at the site of plasmodesmata.