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Effects produced by an intense freezing (-196°C) on the fine structure of vegetal cells.

Quelques effets produits par une congélation intense (-196°C) sur la structure fine de cellules végétales.

Author(s) : GENEVES L.

Type of article: Article, IJR article

Summary

Sporogenic cells of a Bryophyte (Platyhypnidium riparioides) were treated with liquid nitrogen (15 min), and ultrathin sections were studied by ultrastructural techniques. When the samples were frozen after glutaraldehyde fixation, the ultrastructures of the organelles were about the same as for the test group. When the samples were frozen before fixation, the plastids were clear, and hypertrophied, while the mitochondria did not undergo modification. Some properties of cytomembranes were changed, in certain specific organelles only. When the samples were frozen, in the mucilaginous envelope around the sporocyte, the reactivity of the polysaccharidic fibrils to cytochemical reaction PATAg, was positive but slightly reduced In the same structures, the PTA reaction at Iower pH was considerably diminished. The nuclear envelope, the elements of the endoplasmic reticulum, and the Golgi apparatus were darkened when using the technique of metallic impregnation by OsO4 and ZnI2. If the samples are frozen at -196°C, before impregnation, the nuclear envelope fails to react. The majority of the saccules of the reticulum were not impregnated; several were vesiculated and darkened. In the dictyosomes, a few saccules were darkened, but on their periphery the fenestrated structure disappeared. In the sporogen cells studied, the short freezing process by liquid nitrogen modified various structures (plastids, saccules of reticulum or dictyosomes...). It altered specific properties of certain cytomembranes. It maintained the polysaccharidic fibrils of the mucilaginous envelope, but altered their reactivity.

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Pages: 151-156

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Details

  • Original title: Quelques effets produits par une congélation intense (-196°C) sur la structure fine de cellules végétales.
  • Record ID : 30000720
  • Languages: French
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 1 - n. 3
  • Publication date: 1978

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