Moore R, Smith H S
Department of Biological Sciences, Wright State University, Dayton, Ohio 45435.
Am J Bot. 1990 Jun;77(6):727-35.
Epidermal differentiation in primary roots of Zea mays was divided into six cell types based on cellular shape and cytoplasmic appearance. These six cell types are: 1) apical protoderm, located at the tip of the root pole and characterized by periclinally flattened cells; 2) cuboidal protoderm, located approximately 230 microns from the root pole and characterized by cuboidal cells; 3) tabular epidermis, located approximately 450 microns from the root pole and characterized by anticlinally flattened cells; 4) cuboidal epidermis, located approximately 900 microns from the root pole and characterized by cuboidal cells having numerous small vacuoles; 5) vacuolate cuboidal epidermis, located approximately 1,500 microns from the root pole and characterized by cuboidal cells containing several large vacuoles; and 6) columnar epidermis, located approximately 2,200 microns from the root pole (i.e., at the beginning of the zone of elongation) and characterized by elongated cells. We also used stereology to quantify the cellular changes associated with epidermal differentiation. The quiescent center and the apical protoderm have significantly different ultrastructures. The relative volume of dictyosomes increases dramatically during the early stages of epidermal differentiation. This increase correlates inversely with the amount of coverage provided by the root cap and mucilage.
基于细胞形状和细胞质外观，玉米初生根中的表皮分化被分为六种细胞类型。这六种细胞类型分别是：1）顶端原表皮，位于根极顶端，其特征是细胞平周扁平；2）立方形原表皮，位于距根极约230微米处，其特征是细胞呈立方形；3）平板状表皮，位于距根极约450微米处，其特征是细胞垂周扁平；4）立方形表皮，位于距根极约900微米处，其特征是含有许多小液泡的立方形细胞；5）液泡化立方形表皮，位于距根极约1500微米处，其特征是含有几个大液泡的立方形细胞；6）柱状表皮，位于距根极约2200微米处（即伸长区开始处），其特征是细胞伸长。我们还使用体视学方法来量化与表皮分化相关的细胞变化。静止中心和顶端原表皮具有显著不同的超微结构。在表皮分化的早期阶段，高尔基体的相对体积急剧增加。这种增加与根冠和黏液提供的覆盖量呈负相关。
