Ultrastructure of Resin Ducts in Pinus halepensis Development, Possible Sites of Resin Synthesis, and Mode of its Elimination from the Protoplast

Development of the resin duct cavity, sites of resin synthesis in the epithelial cells and elimination of resin from the protoplast were studied in roots of young Pinus halepensis seedlings. It is suggested that the Golgi bodies are involved in dissolution of the middle lamella in the region of the future duct cavity by secretion of lytic enzymes into the cell walls. In early stages of duct development osmiophilic droplets were observed in plastids, periplastidal and cytoplasmic ER, Golgi vesicles, mitochondria, nuclear envelope and in the cytoplasm. In the latter they were often observed to be surrounded by a membrane. Electron micrographs suggested that elimination of resin droplets from the protoplast occurs by their becoming surrounded by plasmalemma invaginations.