The Ultrastructure of the Alkaloidal Vesicles of Papaver somniferum latex

Papaver somniferum latex contains abundant small vesicles. Theirultrastructure was studied in tissue sections from adult plantsand in sections of sequential fractions of centrifuged latex.The vesicles were found to exist in two forms, the first witha smooth but progressively granulated outer membrane and thesecond, probably derived from the first, with adherent ‘cap-like’structures which in the heavier centrifuged fractions possesseda zonally-ordered interior. These vesicle fractions were active in synthesizing morphineand the name ‘alkaloidal vesicle’ is proposed forthem. Papaver somniferum latex also contains an organelle whichwas found to resemble a complex organelle present in the latexof Hevea brasiliensis. Its function is not yet known.