Ultrastructure and cytochemistry of squamulae intravaginales of the marine angiosperm, Halophila ovalis

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Small delicate structures found in the leaf bases in vegetative buds of the marine angiosperm Halophila ovalis (R. Br.) Hook. f. showed a fine structure of the component cells typical of secretory cells. They are rich in organelles particularly ER, dictyosomes, ribosomes and mitochondria. Endoplasmic reticulum occurs at two localities in each cell, one surrounding the central nucleus and the other in the peripheral regions close to the plasmalemma. Groups of dictyosomes occur between the two layers of ER and each group is separated from another by interconnecting strands of ER. A mucilaginous secretion accumulates on the cell surface and between the outer and inner layers of cell wall, particularly at the corners. The involvement of ER in the secretion of mucilage is discussed. Staining of ultrathin sections with silver proteinate after thiocarbohydrazide showed the presence of insoluble carbohydrates and histochemical tests with alcian dyes showed the secretion to contain non-sulphated acid polysaccarides. Staining of epoxy resin sections with Coomassie blue R250 indicated that the mucilage secretion on the surface of and within the cell walls also contained proteins. Cellulase–gold complex marked the cellulose wall layers as distinct from the included secretion. Klein, delikate strukture wat by die blaarbasisse in vegetatiewe knoppe van die marine angiosperm Halophila ovalis (R. Br.) Hook. f. gevind is, het ’n fyn struktuur van saamgestelde tipiese afskeiselle getoon. Hulle is ryk aan organelle, veral endoplasmiese retikulum (ER), diktiosome, ribosome en mitochondria. ER het op twee plekke in elke sel voorgekom, romdom die sentrale kern asook in die periferale dele na aan die plasmalemma. Groepe diktiosome kom tussen die twee lae van ER voor en elke groep is van die ander geskei deur aaneengeskakelde stringe van ER. Slymerige afskeiding versamel op die seloppervlak en tussen die binneste en buitenste selwandlae, veral in die hoeke. Die betrokkenheid van ER in die afskeiding van slym word bespreek. Kleuring van ultradun snitte met tiokarbohidrasied gevolg deur silwer-proteïnaat het getoon dat onoplosbare karbonate teenwoordig is en histochemiese toetse met alcian-kleurstowwe het aangetoon dat die afskeiding nie-sulfaat-suur polisakkariedes bevat. Kleuring van epoksiharsseksies met Koomassie-blou R250 het aangedui dat die slymafskeiding op die oppervlak en ook binne die selwande proteïne bevat. Behandeling met ’n sellulase-goudpeilstaafhet die sellulose selwande van die sekresie onderskei.