pellicle

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Pellicula (from Latin pellicula "fur", "skin"), in English also pellicle, are called different, not always homologous cell envelopes around unicellular algae or protists . In many groups, it refers to an, unspecified, external structure from the cell membrane with various types of thickening underneath (alternatively also called cortex or ectoplasm). With the ciliates , pellicula refers to the outer part of the cell, consisting of the cell membrane, vacuoles called alveoli and the outer layer of the cytoplasm called epiplasm. In the case of the dinoflagellates , the term is used for the wall structure of temporary cysts after they have shed their permanent shell (called theka or theca ). In the Chlamydomonadales , the term refers to a membrane made of aggregated cells, which can form when the zygotes of different mating types meet .

Due to its ambiguity, Preisig and colleagues recommended that the expression be dropped.

Pellicula of the Euglenida

The pellicle of the Euglenida is an envelope structure of the individual cells consisting of proteins and sitting directly under the cell membrane . In the eye animal ( Euglena ) it consists of strip-like plates that can be moved against each other. In others like Phacus , they can form a rigid, interconnected shell. The stripes visible in the light microscope consist of rib-like protein structures with accompanying microtubules and endoplasmic reticulum , they are held together by overlapping at the edges and fibrous connections to the cell skeleton. They can have outwardly protruding tips and other protrusions. The number of stripes is often constant, around 40 in Euglena gracilis . Their width is different; the narrowest are no longer resolved in the light microscope. The stripes can be straight or twisted (spiral). Usually the strips of the pellicle have a thickened and a thinner edge, the thin one is folded over and bent over the thicker one, so that a flexible structure results.

Euglena is able to change its shape to a considerable extent despite the solid shell (so-called "euglenoid" movement). The pellicle of the euglenida was often referred to by the synonymous term periplast .

Individual evidence

  1. ^ Rudolf Röttger: Dictionary of Protozoology . In: Protozoological Monographs , Volume 2, Shaker, Aachen 2001, p. 165, ISBN 3-8265-8599-2
  2. ↑ a b c d e H.R. Preisig, OR Anderson, JO Corliss, Ø. Meestrup, MJ Powell, RW Robertson, R. Wetherbee: Terminology and nomenclature of protist cell surface structures. Protoplasm 181: 1-28.
  3. ↑ James R. Rosowski: Photosynthetic Euglenoids. In: John D. Wehr & Robert G. Sheath (editors): Freshwater Algae of North America. Ecology and Classification. Academic Press, Amsterdam etc. 2003.
  4. ^ Robert Edward Lee: Phycology. Cambridge University Press, 3rd edition 1999. ISBN 0-521-63090-8 . Chapter 6 Euglenophyta.
  5. ↑ Volker Storch, Ulrich Welsch: Kükenthal - zoological internship. Springer-Spektrum-Verlag, Berlin and Heidelberg 27th edition 2014. ISBN 978-3-642-41936-2 . Euglena viridis on page 24 ff.