Browsing by Subject "Ultraestructura"

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    Ultraestructura de los órganos ectodérmicos ampulares en las larvas de dos especies de ascidias (Tunzcata)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1990) Turón, Xavier; Facultad de Biología
    Se estudian aspectos ultrastructurales de los órganos ectodérmicos ampulares de las larvas de Diplosoma spongiforme (Giard) y Polysyncraton lacazei (Giard) (familia Didemnidae). En ambas especies se trata de órganos tubulares formados por células glandulares secretoras. Los órganos ampulares de Diplosoma spongiforme producen una secreción electrodensa en su zona distal, mientras que las células de las paredes laterales presentan una marcada vacuolización del citoplasma apical. Estas características no se han observado en Polysyncraton lacazei. El desarrollo postmetamórfico de los órganos ampulares en ambas especies es también distinto. Se discute la posible función de estos órganos en la fijación al sustrato de las larvas y en la producción de túnica.
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    Ultrastructure of the mycorrhiza formed by Tetraclinis articulata (Vahl) Masters (Cupressaceae)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2004) Honrubia García, Mario; Morte Gómez, María Asunción; Biología Vegetal; Facultad de Biología
    The structural organisation of the endomycorrhiza in naturally infected seedlings and micropropagated and Glomus inoculated plants of Te- traclinis articulata was studied by means of light and electron micros- copy. Hyphal spread from cell to cell in the host root was entirely inter- cellular. Intracellular hyphae crossing through the host walls were ne- ver observed. This could be favoured by the presence of numerous wall swellings at the contacting area among cell walls which are cha- racteristic of T. articulata roots. These wall swellings could impede the crossing of the hyphae. The reduced interfacial region between both symbionts was observed with a fibrillar material in contact with the hyphal wall and, in some cases, in contact with the host plamalemma, although sometimes this region was occupied by small vesicles. The increase of the cytoplasmic organules both in the host cell and intrace- llular hyphae, during the arbuscular phase, indicated an increase of the metabolic activity of both symbionts. The membrane formations, gene- rally referred to as plasmalemmasomes, appeared in the arbuscular interfacial zone and in the cytoplasm of the arbuscular hyphae. This is a typical arbuscular mycorrhiza.