Observations of calcium oxalate crystals of the stem of an energetic plant S. hermaphrodita (L.) Rusby from the Malvaceae family, were performed using LM, DIC, and CLSM microscopes. The transversal and longitudinal sections showed the presence of calcium oxalate crystals in the parenchymal tissue distributed in various layers of the stem. The crystals occurred only in the form of druses. In the innermost part of the stem, i.e. in the pith, the calcium oxalate crystals occurred singly in individual cells. In the parenchyma cells separating sclerenchyma fibres and adjacent to the xylem, the crystals were observed individually in single cells, but the cells containing druses formed rows consisting of even several cells. The cortex contained the different-size druses scattered randomly within the cells. Druses differ in shape and size but they do not protrude beyond the cells although they very often fill them completely. The functions of calcium oxalate crystals are discussed.
The ultrastucture of mesophyll cells of Deschampsia antarctica Desv. (Poaceae) leaves was investigated using the standard method of preparing material for examination in transmission electron microscopy (TEM). The investigated leaves were collected from the Antarctic hairgrass growing in a tundra microhabitat and representing xermorphic morphological and anatomical features. The general anatomical features of mesophyll cells are similar to those in cells of another grass leaves. The observations of the ultrastructure of mesophyll cells have shown that the organelles are located close to each other in a relatively small amount of the cytoplasm or closely adhere to each other. Organelles such as mitochondria, peroxisomes, and Golgi apparatus, as well as osmiophilic materials are gathered close to the chloroplasts. The chloroplast of the mesophyll cells of the D. antarctica leaf can form concavities filled with the cytoplasm. Such behaviour and ultrastructure of organelles facilitate exchange/flow of different substances engaged in the metabolic activity of the cell between cooperating organelles.
PL
Przy użyciu standardowej metody przygotowywania materiału, badano ultrastrukturę komórek mezofilu liści Deschampsia antarctica Desv. (Poaceae) w mikroskopie elektronowym transmisyjnym (TEM). Badane liście zostały zebrane z okazów śmiałka antarktycznego rosnącego w mikrośrodowisku tundrowym, reprezentujących kseromorficzne cechy morfologiczne i anatomiczne. Ogólne cechy anatomiczne komórek mezofilu są podobne do komórek liści innych traw. Obserwacjeultrastruktury komórek wykazały, że organelle komórek mezofilowych występują blisko siebie w stosunkowo niewielkiej ilości cytoplazmy lub ściśle przylegają do siebie. Organelle takie jak mitochondria, peroksysomy, aparaty Golgiego, a także osmofilne materiały gromadzą się w pobliżu chloroplastów. Chloroplasty komórek mezofilu D. antarctica często mają wklęsłości wypełnione cytoplazmą. Takie zachowanie i budowa ultrastrukturalna organelli ułatwia wymianę/przepływ różnych substancji zaangażowanych w aktywność metaboliczną między współdziałającymi organellami komórki.
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