构树形成层细胞超微结构的周期性变化

构树(Broussonetia papyrifera)形成层细胞超微结构具有明显的季节性变化,休眠期形成层带细胞壁比较厚,具有许多小液泡,细胞核占细胞体积较大,核质稀疏,内质网为光滑型,核糖体分散在细胞质中,脂质体较多,活动期形成层带细胞层数较多,细胞壁比较薄,纺锤状原始细胞中具1—2个大液泡,而射线原始细胞具许多分散的液泡,这在双子叶植物中还未报道过,细胞质沿细胞壁分布,核膜明晰,核质浓密,内质网为粗糙型,上面附有大量的核糖体,脂质体较少,在休眠和活动期都有淀粉积累,线粒体、微管和内质网大量分布在初生纹孔场附近,而且有大量的小泡沿细胞壁分布,这有可能与细胞壁的形成有关。

Periodical Variation in the Ultrastructure of Cambial Cells in Brossonetia Papyrifera

The ultrastructure of cambial cells in Broussonetia papyrifera showed seasonal changes. The cells of dormant cambium contained much small vacuoles, smooth endoplasmic reticulum (ER), inactive dictyosome and many lipid droplets. As cambium became active, the cells contained mainly one large central vacuole with parietal cytoplasm, rough ER, active dictyosome and few lipids. Starch grains appeared both in the active and dormant stages, but dormant cambial cells contained more starch than that of active stage. Microtublue. ER and mitochondrin speaded out near pit-field at the dormant and active stage of cambium. However, that ray initial cells contained many small vacuoles at active stage was first reported in the dicotyledon.