Zhu T, Mogensen H L, Smith S E
Department of Biological Sciences, Northern Arizona University, Flagstaff 86011.
Eur J Cell Biol. 1992 Oct;59(1):211-8.
Sperm cells within pollen grains and pollen tubes of alfalfa (Medicago sativa L.) were observed at the ultrastructural level, and their plastid DNA was detected by DAPI (4,6-diamidino-2-phenylindole) staining. One sperm pair within the pollen grain and three sperm pairs within pollen tubes were reconstructed in three-dimensions from serial ultrathin sections. The two sperm cells are linked by cytoplasmic bridges in both pollen grains and tubes, and the vegetative nucleus is closely associated with the sperm cells within the pollen tube. The number of plastids and plastid nucleoids (DNA aggregates) in the sperm cell pair, collectively, is not significantly different from that in the generative cell; however, over 60% of the sperm cell plastids contain no DNA detectable with DAPI. The mean number of mitochondria in sperm cells is reduced from that in the generative cell (from 54 to 17), which suggests that paternal mitochondrial inheritance probably does not occur in the genotype investigated. Sperm cells of a pair may vary in their shape within the pollen grain and tube, but the number of plastids and mitochondria is not significantly different between the sperm cells. Therefore, heterospermy is not a factor determining cytoplasmic inheritance patterns in this species.
在超微结构水平上观察了紫花苜蓿（Medicago sativa L.）花粉粒和花粉管中的精子细胞，并通过4,6-二脒基-2-苯基吲哚（DAPI）染色检测其质体DNA。从连续超薄切片中三维重建了花粉粒中的一对精子和花粉管中的三对精子。在花粉粒和花粉管中，两个精子细胞都通过胞质桥相连，营养核与花粉管中的精子细胞紧密相关。精子细胞对中质体和质体类核（DNA聚集体）的总数与生殖细胞中的总数没有显著差异；然而，超过60%的精子细胞质体不含DAPI可检测到的DNA。精子细胞中线粒体的平均数量比生殖细胞中的减少了（从54个减少到17个），这表明在所研究的基因型中可能不存在父系线粒体遗传。一对精子细胞在花粉粒和花粉管中的形状可能不同，但精子细胞中的质体和线粒体数量没有显著差异。因此，异精现象不是决定该物种细胞质遗传模式的因素。
