罗汉松雄球花及其雄配子体发育的形态结构

该研究采用光学显微镜和扫描电镜，观察罗汉松雄球花、小孢子及其配子体发育过程的形态结构特征，以揭示罗汉松小孢子的发生和雄配子体的发育规律，为罗汉松的生殖和杂交组合提供胚胎学证据。结果发现：(1)罗汉松花芽于每年的7月开始分化，至次年5月花粉成熟散粉，雄球花由单生的卵圆形转为2~3个葇荑花序并生，小孢子叶螺旋状着生于圆柱状的花序轴上，每一小孢子叶远轴面基部并列着生2个小孢子囊。(2)小孢子囊壁发育过程中由外及里出现各由1层薄壁细胞组成的表皮、药室内壁、中层和绒毡层，至散粉前，后两者基本被分解吸收。(3)同一小孢子囊内的造孢细胞发育在时间上存在差异，小孢子母细胞减数分裂后形成的四分体有四面体型和十字交叉型两种排列方式，成熟的雄配子体包括生殖细胞和粉管细胞，发育过程中出现的第一和第二原叶细胞大部分被分解消失。(4)电镜下罗汉松花粉粒为典型的松花型花粉，两侧各具1个气囊，远极面具一萌发沟，花粉粒表面具纹理或皱褶。

Developmental Morphology and Structure of Male Cone and Macrogametophyte of Podocarpus macrophyllus

With Optical microscope and scanning electron microscope (SEM), the study carried out on the morphological and structural traits of the development process of Podocarpus macrophyllus male cones, microspores and gametophytes, so as to reveal the microsporogenesis and the development law of male gametophyte, and provide embryological evidence for the reproduction and cross combination of P. macrophyllus. Results showed that: (1) the male cone of P. macrophyllus differentiates in July each year, and the pollen maturation was in May of the following year. In this period of time, the male cone had developed from single oval to two or three adnate catkins. Microspore leaves spirally grew on cylindrical inflorescence axis, and two microsporangiums coalesced at the base of abaxial surface of each microspore leaf. (2) During the development of microsporangium wall, epidermis, endothecium, middle layer and tapetum appeared from outside to inside, and each of them composed of one layer of thin walled cells. Before shedding, the latter two were decomposed and absorbed. (3) There were differences in the development time of sporogenous cells in the same microsporangium, and the tetrad that formed after the meiosis of the microspore mother cell had two types of arrangement: tetrahedral and decussate types. Mature male gametophyte comprised germ cells and pollen tube cells, and the first and second prothallial cells that appear during development had resolved and disappeared. (4) Electroscope images showed that the pollen grains of P. macrophyllus are typical pine type pollens with one air sac on each side and a germinal furrow on the far pole surface and the surface of pollen was textured or wrinkled. These results may provide an embryological basis for the reproduction and hybrid combination.