玉兰油细胞发育和挥发油产生的超微结构

利用超薄切片和透射电镜研究了玉兰（Magnolia denudata Dest.）油细胞的发育过程，结果表明：成熟油细胞的结构特征是具有3层细胞壁－－初生纤维素壁层、木栓质化壁层和内纤维素壁层，杯形构造，特化的胞间连丝和油囊，油细胞发育过程可划分为初生纤维素壁层、木栓质化壁层形成和内纤维素壁层形成3个阶段，其挥发油在细胞质和质体内合成。在油细胞发育早期，挥发油就以小滴形式开始在细胞质中产生，然后逐渐与油囊融合直接贮入油囊，与此同时，质体中也合成嗜锇物质，以后随质体解体进入细胞质中，再通过杯形构造积累入油囊。油囊中积累的油经OsO4染色后呈灰色，可分为两层，外层较内层，可能与油的两种来源有关。

Ultrastructural studies on the oil cell development and oil accumulation in theMagnolia denudata

The development of the oil cell in Magnolia denudata Desr. was studied with the electron microscope. The results showed that The typical structural characteristics of oil cells include the presence of a tripartite cell wall, in which the outer and inner layers are cellulose, the middle layer is a suberin layer lamellated; presence of a cupule attaching the oil vacuole to the wall; presence of plasmodesmata occurring in wall protuberances. Ultrastructural observations during the development of the oil cell suggested that the oil is produced in two methods in the oil cell of Magnolia denudata . First, the oil occurs as small droplets or in small vacuoles in the cytoplasm, then coalesced into the oil vacuoles. Second, the biosynthesis of the oil occurs in the plastids, then the oil moves into the cytoplasm with the disintegrating of plastids, subsequently into the oil vacuoles through the cupule. The oil drop stained with OsO 4 shows two layers, the outer layer is deeper than the inner one.