CELL TYPE	CYTOPLASMIC FEATURES	CELL WALL FEATURES	3-D GEOMETRY
Sieve Tube Element  Series of Sieve Tube Elements are longitudinally joined end to end via sieve plates  to form Sieve Tubes. Closely associated with parenchyma cells called Companion Cells	No nucleus at maturity No chloroplasts No mitochondria Cytoplasm consists of P2 protein fibrils (slime) and Convoluted and vesiculated Endoplasmic Reticulum in a parietal position (around the circumference of the cell)	Thickened primary cell wall with specialized primary pit fields called Sieve Plates (Transverse end walls) with large pores associated with callose.	Transverse Isodiametric Longitudinal  Elongated cylinder with oblique or transverse end walls (Sieve Plates). Longest axis is in vertical direction.