分株紫萁卵发生的超微结构

摘要

用透射电镜对蕨类植物分枝紫其(Osmunda cinnamamae L. var.asiatica Fernald)卵发生进行了超微结构的研究.卵发生过程中,许多泡囊不仅移向细胞周围,而且在细胞质膜内排为一列,并通过胞吐作用聚集在细胞质膜外,它们释放或分泌嗜锇物质.观察到少数泡囊内含片层状结构的嗜饿物质紧贴于细胞质膜,似乎将其冲破.与此同时,在卵细胞和颈卵器壁之间形成分离腔,其宽度大于以往报道的真蕨类,在卵细胞质膜外出现额外的卵膜,其宽度大于蕨属和鳞毛蕨属.造粉体被大型常呈三角状半圆形或近椭圆形的淀粉粒所充满,当卵成熟时逐渐减少.核大型平扁状,核内出现2~3对平行的双层膜,紧贴核膜.未发现核外突.线粒体一度似不发育,最后恢复正常.%The ultrastructure of oogenesis in the fern Osmunda cinnamomea L. var. asiatica Fernald hasbeen studied by electron microscopy. During oogenesis, numerous vesicles not only moved towards theperiphery, but also were arranged in line along the inside of plasmalemma, and in addition aggregatedoutside the plasmalemma by exocytosis. They released or excreted osmiophilic material. It was observedthat a few vesicles containing lamellar osmiophilic material situated closely along the plasmalemma, seemedto break open. Simultaneously, a separation cavity between egg cell and archegonium wall formed. Its widthwas broader than the other advanced ferns reported previously, and an extra egg membrane occurredoutside around the plasmalemma of the egg, its thickness being greater than in Pteridium and Dryopteris.Amyloplasts around the nucleus were filled with large triangular semicircular or subelliptical starch grains,but as the egg matured they progressively decreased. Nucleus was large and flattened, and paired mem-brahe in two to three couples laid within the nucleus, close and parallel to the nuclear membrane. Nonuclear evagination was observed. Mitochondria seemed to have been undeveloped, but finally recoverednormally.