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Brazilian Archives of Biology and Technology
On-line version ISSN 1678-4324
PAIVA, Elder Antônio Sousa and MACHADO, Silvia Rodrigues. Role of intermediary cells in Peltodon radicans (Lamiaceae) in the transfer of calcium and formation of calcium oxalate crystals. Braz. arch. biol. technol. [online]. 2005, vol.48, n.1, pp.147-153. ISSN 1678-4324. http://dx.doi.org/10.1590/S1516-89132005000100019.
With the objective of studying the connection between calcium oxalate crystals formation and the phloem, fragments of leaves of Peltodon radicans Pohl (Lamiaceae) were fixed and processed, for light and electron-transmission microscopes. It was observed that the crystals occurred in the cells of the bundle sheath, juxtaposed in relation to the phloem. Intermediary cells established a connection between the sieve element and crystal-bearing sheath cells. Calcium was present abundantly in the cytoplasm of sheath cells as calcium oxalate crystals. The presence of calcium was also detected in the intermediary cells, but in the sieve elements it was not detected. There was, therefore, an increasing concentration gradient of calcium in the sieve elements from sheath cells. Thus, we hypothesized that the formation of calcium oxalate crystals regulates calcium levels in the sieve elements.
Keywords : Calcium oxalate; calcium metabolism; companion cells; crystals; Peltodon radicans; phloem.