Differentiation of non-articulated laticifers in poinsettia (Euphorbia pulcherrima Willd.) was studied ultra-structurally. Growing laticifers show: (1) a multinucleate apical region containing abundant ribosomes but few other differentiated organelles and (2) a sub-apical zone where the cytoplasm is dominated by vacuoles of diverse morphology with latex particles. These particles appear first within narrow tubular vacuoles developed especially in the peripheral cytoplasm. During vacuolation of the laticifer, portions of cytoplasm, including some of the nuclei, become isolated by the enlarging and fusing vacuoles; eventually these become lysed, except the latex particles which remain in the central vacuole. During differentiation of a laticifer branch, the cytoplasm contains the usual organelles, including a few microbodies and coated vesicles. The plastids that lie within the peripheral cytoplasm differentiate into amyloplasts with a single elongated starch grain. Towards the end of differentiation the cytoplasm becomes restricted to a thin parietal layer, with the remaining organelles reduced or degenerate, surrounding a central vacuole filled with latex particles.
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B. A. Fineran (1983) studied this question.