Šottníková Anna, Lux Alexander
Department of Plant Physiology, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-2, SK-842 15 Bratislava, Slovak Republic.
New Phytol. 2003 Oct;160(1):135-143. doi: 10.1046/j.1469-8137.2003.00863.x.
• The structure and development of the cortical layers, especially the endodermis and exodermis, and changes in the cortex caused by the secondary growth of vascular tissues are described in the adventitious roots of gentian (Gentiana asclepiadea). • Sections along the whole axis of the soil-grown roots were observed using light microscopy; fluorescence microscopy was used to determine developmental stages of the endodermis and exodermis. • Both endodermis and exodermis develop in three stages: Casparian band formation, suberin lamellae deposition and secondary thickening of walls. After the onset of cambial activity (20 mm from apex) cortical cells expand tangentially and subdivision of individual cells starts between 20 mm and 60 mm from apex. Highly differentiated endodermal cells are divided by 0-19 new anticlinal walls, exodermal cells by 0-3 and parenchymatous mid-cortex by 0-1. • The additional anticlinal cell walls of the endodermis and exodermis possess neither Casparian bands nor suberin lamellae. Suberin lamellae remain continuous on the surface of extended tangential walls of both layers. There is a correlation between increasing diameter of the secondary vascular tissues and the number of endodermal cells created by subdivision of the original cells.
• 描述了龙胆（Gentiana asclepiadea）不定根中皮层各层，尤其是内皮层和外皮层的结构与发育，以及维管组织次生生长引起的皮层变化。
• 使用光学显微镜观察土壤中生长的根沿整个轴的切片；用荧光显微镜确定内皮层和外皮层的发育阶段。
• 内皮层和外皮层均经历三个发育阶段：凯氏带形成、栓质化层沉积和细胞壁次生加厚。形成层活动开始后（距根尖20毫米处），皮层细胞沿切线方向扩展，单个细胞的细分在距根尖20毫米至60毫米之间开始。高度分化的内皮层细胞被0至19条新的垂周壁分隔，外皮层细胞被0至3条分隔，薄壁的中皮层被0至1条分隔。
• 内皮层和外皮层额外的垂周细胞壁既没有凯氏带也没有栓质化层。栓质化层在两层延伸的切向壁表面保持连续。次生维管组织直径的增加与原始细胞细分产生的内皮层细胞数量之间存在相关性。
