Transmission electron microscopy localization of caleosin in the olive tapetum. Sections from olive anthers at the young microspore (A), vacuolated microspore (B), young pollen grain (C) and mature pollen grain (D) stages were incubated with a FL anti-Clo3 Ab, followed by an anti-rabbit IgG-15 nm gold conjugated secondary Ab. Oil body-associated caleosin is indicated by arrowheads, while circles denote ER-associated caleosin. Note that: i) the tapetal cell vesicles fused with the plasma membrane (star), releasing their content to the loculus, and ii) oil bodies merged (arrows) to produce larger OBs and lipoid masses (asterisks). CW: cell wall; En: endothecium; L: anther locule; TC: tapetal cell; T: tapetum.