Paiva Elder Antônio Sousa, Buono Rafael Andrade, Lombardi Julio Antonio
Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Ann Bot. 2009 Feb;103(3):517-24. doi: 10.1093/aob/mcn237. Epub 2008 Dec 1.
The distinction between pearl bodies (or pearl glands) and food bodies (FBs) is not clear; neither is our understanding of what these structures really represent. The present work examined the ontogenesis, structure, ultrastructure and histochemical aspects of the protuberances in Cissus verticillata, which have been described since the beginning of the 19th century as pearl glands or pearl bodies, in order to establish a relationship between their structure and function.
Segments of stems and leaves in different stages of development were collected and fixed for study under light microscopy as well as electron transmission and scanning microscopy. Samples of FBs were subjected to chemical analysis using thin-layer chromatography.
The FBs in C. verticillata are globose and attached to the plant by a short peduncle. These structures are present along the entire stem during primary growth, and on the inflorescence axis and the abaxial face of the leaves. The FBs were observed to be of mixed origin, with the participation of both the epidermis and the underlying parenchymatic cells. The epidermis is uniseriate with a thin cuticle, and the cells have dense cytoplasm and a large nucleus. The internal parenchymatic cells have thin walls; in the young structures these cells have dense cytoplasm with a predominance of mitochondria and plastids. In the mature FBs, the parenchymatic cells accumulate oils and soluble sugars; dictyosomes and rough endoplasmic reticulum predominate in the cytoplasm; the vacuoles are ample. Removal of the FBs appears to stimulate the formation of new ones, at the same place.
The vegetative vigour of the plant seems to influence the number of FBs produced, with more vigorous branches having greater densities of FBs. The results allow the conclusion that the structures traditionally designated pearl glands or pearl bodies in C. verticillata constitute FBs that can recruit large numbers of ants.
珍珠体（或珍珠腺）与食物体（FBs）之间的区别并不明确；我们对这些结构的真正本质也了解甚少。本研究对19世纪初就被描述为珍珠腺或珍珠体的白粉藤属植物突起物的个体发育、结构、超微结构和组织化学方面进行了研究，以确定它们的结构与功能之间的关系。
收集不同发育阶段的茎段和叶片并固定，用于光学显微镜、透射电子显微镜和扫描电子显微镜观察。对食物体样本进行薄层色谱化学分析。
白粉藤属植物的食物体呈球形，通过短柄附着于植株上。这些结构在初生生长阶段沿整个茎存在，也存在于花序轴和叶片的背面。观察发现食物体来源混合，由表皮和其下的薄壁细胞共同形成。表皮为单层，具薄角质层，细胞具致密细胞质和大细胞核。内部薄壁细胞具薄壁；在幼嫩结构中，这些细胞具致密细胞质，富含线粒体和质体。在成熟食物体中，薄壁细胞积累油脂和可溶性糖；细胞质中高尔基体和粗面内质网占主导；液泡丰富。去除食物体似乎会刺激在同一位置形成新的食物体。
植株的营养活力似乎会影响所产生食物体的数量，更健壮的枝条食物体密度更高。结果表明，传统上称为白粉藤属植物珍珠腺或珍珠体的结构构成了能吸引大量蚂蚁的食物体。
