Acute inflammation in foetal and adult sheep: the response to subcutaneous injection of turpentine and carrageenan.

Because of the small number of inflammatory cells found in skin wounds, it has been considered that foetal sheep are incapable of an adequate inflammatory response. The present study shows that subcutaneous injection of turpentine or carrageenan into foetal sheep consistently excites a severe cellular inflammatory reaction. At 75 days gestation the inflammatory cells are all macrophages. As the foetus develops, polymorphs play an increasing role in the early response to turpentine. By 120 days inflammatory cells are almost all polymorphs as in adult sheep. However the response to carrageenan remains macrophage in type. At all stages of gestation the acute cellular response is followed by development of scar tissue, more pronounced with turpentine than carrageenan. Any proposed intrauterine surgery must allow for the pronounced and prolonged inflammatory response and scar tissue formation caused by persistent inflammatory stimuli in foetal animals.