Observations on the Development and Fine Structure of the Articulated Laticifers of Papaver somniferum

Abstract

The development and fine structure of articulated anastomosing laticifers in Papaver somniferum were studied. Laticifers are not present in the embryos but differentiate soon after germination and are found in the phloem areas 18–30 h after the seed is sown. Laticifers and sieve elements are generally separated by at least one cell layer in the roots, but in cotyledons, stems, and leaves they usually occur adjacent to each other. As the laticifers differentiate an abundance of vesicles forms in the cytoplasm. This process appears to involve the endoplasmic reticulum and it is suggested that the vesicles may be a specialized form of vacuole. Substances present in the vesicles react strongly with iodine-potassium iodide. Laticifer-cytoplasm persists peripherally and between the vesicles. It contains the usual cell organelles, the presence of which substantiates an active metabolic role for the laticifer contents.