The surface precipitation reaction in the ovarian frog egg

Abstract

Although the formation of a new boundary about the exuded protoplasm of a torn or 'crushed cel l is believed to be a general protoplasmic reaction, if has actual ly been observed in i~elatively fe~(~ types of cells, due largely to limitations o f !echnique. H e j 1 b r u n n (1927) termed this " t h e surface precipi ta t i0n r eac t ion" (abbrevia ted s. p. r.) and showed that it was dependent on the presence of calcium, ions i n the external medium. For references to its description and significance see H e i 1 b r u n n (1928, 1943). The l i terature seems ahnost devoid of observations on ver tebra te cells. H e n s e n (1861) crushed blood cells of the frog and one of his figures shows the formation o~ a new boundary about t h e exuded protoplasm. S e i t c h i k (1957) described the reaction in Amphiuma erythrocytes . H e i l b r u n n (1940), in s tudying the formation of a plug at the cut ends of isolated single muscle fibers of the adductor magnus of the frog, compared it to the s .p . r . The plug material increases at the expense of the intact protoplasm of the fiber. The rate of formation of plug material is increased in the presence of added calcium. There is, however, one impor tan t difference which has not been exper imenta l ly resolved. If the fiber is placed in oxalate or ci trate solutions, which remove near ly all the free calcium from the external medium, the reaction is not prevented. Types of cells suitable for the s tudy of the reaction must possess certain_ characteristics. One should be able to obtain single cells free of the breakdown products of other cells. They should be large enough to

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