Paiva E A S, Machado S R
Department of Botany, Institute of Biological Sciences, Federal University of Minas Gerais, CEP 31270-901, Belo Horizonte, MG, Brazil.
Braz J Biol. 2006 Feb;66(1B):301-8. doi: 10.1590/s1519-69842006000200012. Epub 2006 May 15.
Colleters are widely distributed and have been reported in several taxa. However, the only report of colleters in the Caryocaraceae family is in Caryocar brasiliense. This study purports to describe the distribution, structure and ultrastructure of colleters in C. brasiliense. Vegetative shoot apices with stipules in different stages of development were collected, fixed, and processed by light, transmission and scanning electron microscopy. Colleters occur on the stipule adaxial face and are differentiated on younger stipules, remaining functional until senescence. Stipules are deciduous, falling before the beginning of leaf expansion. Colleter secretion is abundant, filling all the space delimited by the stipule. Colleter origin is mixed, involving the protoderm and ground meristem. In this species, colleters are finger-shaped, consisting of a column of non-secretory central cells and a secretory epithelium whose cells are arranged in palisades. Secretory epithelium cells show dense cytoplasm, rough endoplasmic reticulum (RER) segments, free ribosomes, mitochondria, and abundant well developed dictyosomes. The colleters central cell shows a flocculated cytoplasm and developed vacuole. These cells have a small lobated nucleus with an inconspicuous nucleolus. Mitochondria and RER stand out in the organelles. There is evidence of granulocrine secretion and colleter involvement with protection of the apical meristem and leaves in the initial stages of development.
脂腺广泛分布，在多个分类群中都有报道。然而，关于油桃木科植物脂腺的唯一报道是在巴西油桃木中。本研究旨在描述巴西油桃木中脂腺的分布、结构和超微结构。采集了处于不同发育阶段且带有托叶的营养枝顶端，进行固定，并通过光学显微镜、透射电子显微镜和扫描电子显微镜进行处理。脂腺出现在托叶的正面，在较幼嫩的托叶上分化形成，直至衰老仍保持功能。托叶是落叶性的，在叶片展开之前脱落。脂腺分泌丰富，充满托叶界定的所有空间。脂腺起源混合，涉及原表皮和基本分生组织。在该物种中，脂腺呈手指状，由一列非分泌性的中央细胞和一层分泌上皮组成，分泌上皮细胞呈栅栏状排列。分泌上皮细胞显示出致密的细胞质、粗面内质网片段、游离核糖体、线粒体以及丰富且发育良好的高尔基体。脂腺中央细胞显示出絮状细胞质和发达的液泡。这些细胞有一个小的叶状核，核仁不明显。线粒体和粗面内质网在细胞器中较为突出。有证据表明存在颗粒分泌，并且脂腺在发育初期参与对顶端分生组织和叶片的保护。
