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冷冻扫描电镜揭示橡胶树初生乳管的有节连接结构特征
Cryo-SEM Reveals Articulated Anastomosing Primary Laticifers in Rubber Tree Stems
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摘要: 为明确巴西橡胶树初生乳管结构类型长期存在的争议,进而从解剖学层面深入解析乳管发育机制,利用冷冻扫描电子显微镜(Cryo-SEM)技术,对橡胶树无性系7-33-97的幼嫩茎和成熟茎初生乳管区域内进行了系统的观察。结果表明:在电镜视野下,初生乳管的典型特征为腔体内充满富含颗粒的海绵状结构。在横切视野下,相邻乳管之间常出现局部侧壁融合,融合处壁层变薄或局部缺失,腔体原生质连续,显示出横向连接的结构特征。在纵切视野下,乳管沿茎轴方向排列成连续的管状结构,相邻细胞的端壁处可见融合后的残迹,显示出有节乳管的结构特征。横、纵切观察结果共同表明,橡胶树初生乳管具有细胞间壁层融合与原生质贯通的特征,证实属于有节连接乳管类型。因此,通过Cryo-SEM技术获得了初生乳管细胞间连接的直接形态学证据,明确其属于有节连接乳管类型。Abstract: To obtain more reliable direct evidence to resolve the long-standing controversy over the structural type of primary laticifers in Hevea brasiliensis and provide anatomical insights into laticifer development , we employed cryo-scanning electron microscopy (Cryo-SEM) to systematically examine primary laticifer regions in young and mature stems of the rubber tree clone 7-33-97.The results showed that, under Cryo-SEM, primary laticifers typically exhibited a lumen filled with a particle-rich, sponge-like matrix. In transverse views, adjacent laticifers frequently showed localized lateral fusion, where wall layers became thin or were locally absent and the lumenal protoplasm appeared continuous, indicating lateral intercellular connections. In longitudinal views, laticifers formed continuous tubular files along the stem axis, and fusion remnants were observed at the end walls between adjacent cells, consistent with an articulated organization. Together, the transverse and longitudinal observations demonstrate that primary laticifers possess intercellular wall fusion and protoplasmic continuity, supporting their identification as articulated anastomosing laticifers. In summary, this study provides direct ultrastructural evidence for intercellular connectivity in primary laticifers , confirming their identity as articulated anastomosing laticifers.
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