Место издания:The Gold Coast Marina Club Guangzhou, China
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Аннотация:Fruits of Tupidanthus calyptratus were studied at the level of synascidiate zone, where multiple seed cavities are surrounded by fibers of the pyrene. At this level, a well-developed network of anastomosing secretory canals was found. Scattered secretory canals (usual for Araliaceae) lacking distinct connection with vascular bundles are numerous in all parts of the pericarp of the inferior fruit, both in the ovary and the floral tube. The length and orientation of these canals are diverse, but all of them have pronounced epithelial sheaths.
The secretion found in canals was transparent, from colourless to light-yellow, without any specific smell, not viscous. It was found to be extremely hydrophobic: failed to dissolve in water or 50% ethanol, only partly dissolved in 70% ethanol. Histochemical tests with strong alcohol diluted or aggressive reagents were done to reveal its composition. Staining tests with Sudan Black and Sudan III in 85% ethanol for total lipids, concentrated sulfuric acid for terpenoids (sesquiterpenes) were positive but osmium tetroxide for unsaturated lipids was negative as well as ferric chloride in 60-85% ethanol for phenolics (tannins), vanillin in ethanol/hydrochloric acid, Naturstoff and aluminum chloride for phenylpropanoids, iodine/potassium iodide for alkaloids, and NADI reagent for terpenoids.
Based on these results, a suggestion was made about oils being the major component of secretion.
In the transmission electron microscope study, the secretion looked like homogeneous substance of very low electron density. Secretory epithelial cells, unlike parenchymal ones, were thin-walled, with the nucleus pressed to the outer cell wall by the large transparent vacuole; plastids were leucoplasts with solitary thylakoids, roundish or elongated in sections, containing no or little starch. Smooth endoplasmic reticulum prevailed over granular one in secreting cells, contacts of plastid envelope and reticular elements were not extended. The ultrastructure of epithelial cells was similar to that of oil-secreting cells of oil cavities and oil glands and this corroborates the conclusion regarding the secret composition.