黄芩根中木间木栓的形成与发育特性研究

应用光学显微镜和电子显微镜对3年生黄芩(Scutellaria baicalensis Georgi)根中木间木栓的形成及其发育过程进行了细致观察，以揭示黄芩木间木栓形成的特征以及发育过程中导管及周围薄壁细胞的变化，旨在为中药枯芩的形成提供理论依据和实验证据。结果表明：(1)黄芩根的次生结构由周皮、皮层和次生维管组织组成；木间木栓发生在木质部异常导管的周围，先是导管内出现侵填体或其他物质，接着这些导管邻近的部分薄壁细胞内也出现一些物质，随后导管外围的正常薄壁细胞恢复分生能力，产生木栓形成层，进而形成木间木栓。(2)木间木栓将健康组织与这些异常的导管和薄壁细胞隔离，隔离在内的组织会逐渐成为死亡组织。(3)横切面观，小木间木栓可同时或先后发生在木质部的不同位置，由内向外逐渐扩大，与周围的木间木栓相连，最终形成大的木间木栓。(4)纵切面观，木间木栓以管状形式由根头部向下延伸，部分根中距根头部以下3 cm内有木间木栓存在。

Developmental Characteristics of Interxylarycork in the Root of Scutellaria baicalensis Georgi

We used Optic Microscopic and Electron Microscopic to observe the formation and development of the interxylarycork in the roots of three year old Scutellaria baicalensis, to reveal the characteristics of interxylarycork formation and the changes of the vessels and surrounding parenchyma cells during the development of interxylarycork, in order to provide theoretical basis and experimental evidence for the formation of pith decayed products of Radix Scutellariae.The results showed that: (1) the secondary structure of S. baicalensis root was composed of periderm, cortex and secondary vascular tissue; Interxylarycork occurred around the abnormal vessels in the xylem. First, tylosis or other substances appear in the vessels, and then some substances also appear in the parenchyma cells adjacent to these vessels. Subsequently, the normal parenchyma cells around the vessels recovered their meristematic ability and produced cork cambium, which formed interxylarycork. (2) Interxylarycork separated healthy tissues from these abnormal vessels and parenchyma cells, and the isolated tissues will gradually become dead tissues. (3) In the transection section, these small interxylarycorks can occur at different positions of xylem at the same time or successively, they gradually expand from inside to outside and connected with the surrounding interxylarycork, and finally, they formed a large interxylarycork. (4) In the longitudinal section, interxylarycorks which exist in some S. baicalensis roots within 3 cm below the root head extend downward from the head of the roots in tubular form.