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Ultra-Structure of the Choanocyte Collar-Cells in Freshwater Sponges


As early as 1896 Bidder1 mentioned the presence of fibrils in the collars of the relatively large collar cells of calcareous sponges. Later, the very existence of such a structure was denied by several authors though confirmed by a few, particularly De Saedeleer2 and Dubosq and Tuzet3. Kilian4 has succeeded in demonstrating the existence of fibrillar structures in the much smaller collars of siliceous sponge collar cells. That author observed by means of the electron microscope, whole Spongillidae collar cells which were previously dilacerated and fixed. Yet he stated himself that the fixatives he used caused severe contractions of the collars. De Saedeleer2 is the only one who suggested that the collar should be considered as an ‘eel-trap’ made up from separate tentacles.

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  1. 1

    Bidder, G., Quart. J. Micro. Sci., 38, 9 (1896).

  2. 2

    De Saedeleer, H., Ann. Soc. Roy. Zool. Belg., 60, 16 (1929).

  3. 3

    Dubosq, O., and Tuzet, O., C.R. Soc. Biol., Paris, 129, 296 (1938).

  4. 4

    Kilian, E. F., Ber. Oberhessischen Ges. Natur- und Heilkunde, Neue Folge, Naturwiss. Abt., 27, 85 (1954).

  5. 5

    Bouillon, J., Semal, P., and Vandermeerssche, G. (in the press).

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