Ultrastructural study concerning disintegration of fibrin foam used as filling material after partial hypophysectomy in rats.

After partial hypophysectomy in rats, fibrin foam was implanted in the wound cavity. The fate of the implant was followed over a period of time up to three months by light and electron microscopy. First of all granulocytes appeared, whose granules obviously participated in the fragmentation of the fibrin network. Two days after operation and then in rapidly increasing numbers histiocytes could be found which surrounded the fibrin fibres with pseudopodia and absorbed them. They were broken down intracellularly by the lysosomes. In the wound cavity the gradually increasing number of fibroblasts formed collagen that often lay close to the fibrin fibres. The disintegration of the Fibrospum corresponded largely to that of natural native fibrin even though some could be identified three months after operation. The isolated appearance of foreign giant cells argued in favour of a moderate tuberculin type allergic reaction by the rat.