‘Electro-Chemical’ Orientation of Bracken Spermatozoids


THE chemotaxis of bracken spermatozoids, first demonstrated by Pfeffer1, has so far been investigated by introducing a concentrated source of a stimulating substance into a suspension of spermatozoids and observing their behaviour in the resultant chemical gradient. In Pfeffer's original method, a fine glass capillary containing a solution of sodium L-malate provided the source; in these conditions spermatozoids aggregate around the tip (Fig. 1). Such experiments have revealed the highly directional character of the response2, its chemical specificity (salts of L-malic acid and a few closely related dicarboxylic acids are active)3, and that the response depends on the ratio between the applied and background concentrations in the suspension1. To permit more quantitative study of bracken sperm chemotaxis, a search has been made for conditions experimentally more favourable than those obtained with the classical methods of establishing chemical gradients. Two new phenomena, closely related to ‘classical’ chemotaxis, have been observed.

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  1. 1

    Pfeffer, W., Unter. Bot. Inst. Tübingen, 1, 363 (1884).

  2. 2

    Rothschild, Lord, Internat. Rev. Cytology, 1, 257 (1952).

  3. 3

    Rothschild, Lord, “Fertilization” (Methuen and Co., 1956).

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BROKAW, C. ‘Electro-Chemical’ Orientation of Bracken Spermatozoids. Nature 179, 525 (1957) doi:10.1038/179525a0

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