Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis.

Available documentation about the development of the female gametophyte of Crassulaceae is very limited. The aim of this study was to extend the embryological knowledge of Crassulaceae by analysing the development of the embryo sac in Sedum sediforme. Transmission electron microscopy and light microscopy including Nomarski optics (DIC) were used to observe individual stages of female gametophyte development. Cytochemical staining enabled detection of lipids, insoluble polysaccharides and proteins in gametophyte cells during their formation. Their increased accumulation was observed during nucellar cell and unfunctional cell degeneration in the embryo sac at the coenocytic and cellular stages (megagametogenesis). The female gametophyte develops in anatropous, bitegmic and crassinucellate ovules. The mature embryo sac is built of seven cells but after antipodes degeneration it is formed by the egg apparatus and a central cell. The monosporic Polygonum type was observed. One megaspore mother cell (MMC) formed three cells after meiosis. A triad was formed from a functional megaspore (placed chalazally), one uninucleate megaspore and a binucleate cell located at the micropylar end. Plasmodesmata with adhering electron-dense dome were noticed in walls of the coenocytic embryo sac and in the outer walls of ephemeral antipodes. Moreover, similar to synergids, antipodes form wall ingrowths. Here, we report new structural features of the antipodal cells (the presence of plasmodesmata with an electron-dense dome) which have not been described before. This new structural observation indicates that these cells participate in substance transport and that this process can probably be additionally regulated.

Morfoanatomia de folhas de bálsamo: Sedum dendroideum Moc. et Sessé ex DC, Crassulaceae / Leaf morpho-anatomy of Sedum dendroideum Moc. et Sessé ex DC, Crassulaceae

Sedum dendroideum Moc. et Sessé ex DC, Crassulaceae é uma espécie suculenta, conhecida popularmente como bálsamo. Na medicina tradicional, suas folhas são empregadas para tratar inflamações de pele, contusões e problemas gástricos, em razão das ações emoliente e cicatrizante. Com o objetivo de fornecer subsídios morfológicos e taxonômicos, realizou-se estudo morfoanatômico das folhes. Observou-se que as folhas são simples, sésseis e alternas e apresentam formato oboval, levemente assimétrico, com ápice obtuso, base decurrente e margem lisa. A epiderme é uniestratificada e possui células com paredes anticlinais delgadas e onduladas. Os estômatos são anisocíticos, estando presentes em ambas as faces. Mesofilo homogêneo e numerosos idioblastos com conteúdo fenólico foram evidenciados.

[Morphological and histological studies of herba sedum aizoon].

The description characters of Herba Sedum aizoon were recounted. And the histological characters of the root, rhizome, stem, leaf and flower of the plant were reported. The characters of the isolated tissue and powder were also involved. These results provided valuable reference information for putting the medicinal resource to rational exploitage and use.