Active site directed inhibitor used in the production of antibodies against urokinase.

Results The three slides of the serial sectioned material-peroxidase uncounterstained, Perls' Prussian blue, and the peroxidase counterstained with Perls' Prus-sian blue-were carefully compared by matching the architecture of the fields using a comparison bridge. Neither the prolactin nor the haemosiderin components seemed to be diminished as a result of the extra staining procedure. Low background staining resulted from the use of reasonably fresh potassium ferrocyanide crystals; the background staining appeared to increase in proportion to the increased shelf life of the crystals, although this was not measured histoquantitatively. But distinction could still be made between the peroxidase positive staining and the haemosiderin. The increased time in washing after the osmium treatment, when performed with care, did not seem to increase the fragility of the sections, although more vigorous washing for longer periods was not attempted. Discussion Hormone identification plays an important part in the diagnosis of pituitary adenomas. Often, biopsy specimens obtained from surgically removed pituitary gland contain sites of old haemorrhage which are sparse, diffuse, and intermingled with the hormone producing cells. At the sites the differentiation between hormone and haemosiderin must be clear, which is why the technique was originally evaluated. 1191 It has previously been used successfully after the peroxidase-antiperoxidase method of Sternberger and Cucullis4 in renal cell carcinoma,5 where large amounts of iron pigment were present in the section. With the increased use of immunoperoxidase techniques in surgical pathology,6 the addition of this simple but old technique to the modern one could further increase its specificity.tion of prolactin in chromophobe pituitary adenomas: study of necropsy material by immunoperoxidase technique. blood group antigens in gastric carcinoma as demonstrated by the immunoperoxidase technique.