Local Morphological Response Following a Single Subcutaneous Injection of Carrageenin in the Rat

Abstract

A single injection of 0.5 ml of a 2% aqueous solution of carrageenin in the mid-line of the back in the rat caused a local tissue response which was examined grossly, microscopically, and histochemically after the 1st, 2d, 4th, 7th, 14th, 21st, and 28th day. Gross findings and semiquantitative histological analysis indicated a violent inflammatory reaction in the form of an abscess after the 1st to the 4th day, which was later (7th to 28th day) transformed into a fibrous granuloma. Additional wet-weight/dry-weight studies of the excised lesions carried out after the 1st, 2d, 4th, 7th, and 14th day indicated a maximum exudative response after the 1st day. These results show that this polygalactose sulfate causes a more violent inflammatory response in the rat than agar, and that,the rat reacts much more intensely than the guinea pig.