Karina Lucas Barbosa Lopes
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Marcela Thadeo
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Aristéa Alves Azevedo
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Arlete Aparecida Soares
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Renata Maria Strozi Alves Meira
The occurrence of nonarticulated laticifers has been recorded in the literature for Apocynaceae, but little information is available on their structure and the chemical compounds in their latex. The objective of this study was to describe, anatomically and histochemically, the laticifers and latex found in the roots, stems, and leaves of Mandevilla atroviolacea (Stadelm) Woodson, a genus in the Apocynaceae. Laticifer anatomy was examined by light microscopy, and the chemical nature of the exuded latex was studied using cytochemistry. Articulated laticifers were present in M. atroviolacea. The lactiferous system in stems and leaves originated from both procambium and ground meristem, and it was determined to be functional, as indicated by changes in the cytoplasm immediately subsequent to its formation. However, in tuberous roots, laticifers originated from the vascular cambium, phellogen, and parenchymatous cortical cells. The primary wall of laticifers consists of pectins and cellulose and is thicker than that of adjacent cells. The laticifer secretion contained an emulsion of lipophilic substances rich in neutral lipids, resin oils, and possibly rubber. The presence of articulated laticifers is reported for the first time for Apocynoideae, contributing to the knowledge and understanding of these structures in the family Apocynaceae.