沙冬青（Ammopiptanthus mongolicus）小孢子发育的超微结构研究

本文对沙冬青小孢子发育的超微结构进行了观察，主要结果为：１）小孢子母细胞早期壁上有胞间连丝，随着发育，壁上出现了胞质通道．母细胞中内质网、线粒体和质体丰富，细胞处于明显的代谢活跃状态．四分体时期内质网消失．２）在小孢子发育各期质体和线粒体一直存在，细胞质中分布着小液泡，质膜上有泡状内陷．小孢子核靠壁后发生有丝分裂形成两个大小悬殊的细胞，此时，可见到大量的质体集中分布在营养细胞质中靠近生殖细胞壁的附近．３）在小孢子早期，绒毡层中内质网、线粒体和质体丰富，内质网持续产生大量小泡并在其中沉积电子致密物形成球状体（Ｏｒｂｉｃｕｌｅ）．小孢子后期，绒毡层细胞中内质网消失，出现大量的多泡体、球状体和脂体，绒毡层开始解体．在２－细胞花粉时绒毡层的解体产物大量流入花药腔中．

An Ultrastructural Study of the Microspore Development in Ammopiptanthus mongolicus

he present paper deals with the development of microspore in Ammopiptanthus mongolicus.The main results are as follows : 1)In the early stage of microsporocyte development , there areplasmodesmata in the cell wall. With the development of the microsporocyte, some cytoplasmicchannels are present between adjacent microsporocytes. Endoplasmic reticulum , mitochondria,and plastids are abundant in microsporocytes and the prominent metabolic activity of these cells isobserved , but endoplasmic reticulum disappear at tetrad stage.2 ) Plastids and mitochondria arecontinuously present in all developmental stages of the microspore. Some small vacuoles are ran-domly distributed in the cytoplasm. After the nucleus of microspore is close to the microsporewall , the mitosis takes place and two different cells in volume are formed.A lot of plastids arecollected in the vegetative cytoplasm near the generative cell wall,which showed regional distribu-tion. 3)In the early stage of microspore development ,endoplasmic reticulum ,mitochondria ,andplastids are rich in the tapetal cells. Profuse vesicles are continuously produced by endoplasmicreticulum and electron dense substances are dispoited in them. In the late stage of microspore de-velopment ,endoplasmic reticulum disappear and there are abundant orbicules ,polyvesiculate bod-ies, and lipid bodies in tapetal cells.later on,the tapetum begins to degenerate,and the degenerat-ed materials such as orbicules and lipid bodies enormously flow into anther lumen in the stage oftwo-celled pollen grain.