牡丹苗端由营养生长转向生殖生长过程中超微结构研究

电镜观察了营养生长和生殖生长两个发育埋藏的牡丹（Ｐａｅｎｉａ ｓｕｆｆｒｕｔｉｃｏｓａ．）苗端。结果如下：（１）营养生长期，原套和原体的细胞壁厚薄不均，多有胞间连丝分布。两者细胞核内均在较多异染色质。细胞质内含许多质体、嗜锇细胞主少量的线粒体，内质网和高尔基体。质体无片层结构，部分质体有淀粉粒和脂滴。原体细胞的液泡化过程比原套细胞略高。原体下方扁平细胞的大部分空间被大量的淀粉质体和液泡占据，淀粉粒

ULTRASTRUCTURAL STUDY OF SHOOT APEX IN PAEONIA SUFFRUTICOSA ANDR. FROM VEGETATIVE GROWTH TO REPRODUCTIVE GROWTH

Shoot apexes of peony in vegetative growth and reproductive growth were observedwith electron microscope. (1) At the stage of vegetative growth, the thickness of cellwalls in both tunica and corpus is not uniform,and plasmodesmata are seen in most cellwalls. There are a lot of heterochromatin in their nuclei. Many plastids,osmiophilic or-ganelles and a few mitochrondria,endoplasmic reticulum and Golgi bodies are found inthe cytoplasm. The plastids lack lamellar structures,some of them contain starch grainsand lipid drops. The corpus cell is slightly more vacuolate than the tunica cell. Flat cellunder corpus is occupied mainly by rich starch-containing plastids and vacuoles. On theedges of starch grains and cell walls,a lot of transparent electron-density materials lie.(2) At the stage of reproductive growth, osmiophilic organelles, lipid drops and small vacuoles show an increased number in mantale cell,core cell and the flat cell under core.In addition,the heterochromatin decreases in the mantale nucleus. Abundant plasmodes-mata present in the position of thin walls of core cell which still has a lot of heterochro-matin. In the flat cell,the number of starch-containing plastids reduced sharply.