Abstract
A fluorescein labelled extract of Ulex europeus seed was found to be satisfactory for demonstrating water soluble H antigen in formalin fixed paraffin embedded tissue sections. Commercially available anti-A typing serum was labelled with fluorescein and used to demonstrate water soluble A antigen in formalin fixed paraffin embedded tissues. The reactivity of A and H antigen after neutral buffered formalin fixation was superior to that observed after Zenker's, Helly's or Bouin's fixation; reactivity in paraffin sections of formalin fixed tissues were equal to that of fresh frozen sections. Autolysis did not prevent the demonstration of blood group antigen A or H in fixed paraffin embedded tissues but was associated with some diffusion of the antigens.
The distribution of H antigen in formalin fixed paraffin embedded tissue section for patients with type A, B and O blood also was studied. In secretors blood group substances were widely distributed in the epithelial mucins of the body whereas in nonsecretors the antigens are largely confined to the deep portion of the pyloric mucosa of the stomach and Brunner's glands. The distribution of A and H antigen within a gland, such as Brunner's glands, was not homogeneous. That is, some acini contained A antigen but no H antigen; others contained H antigen but no A antigen: a few contained both A and H antigen. The significance of this mosaic distribution which previously has not been described was discussed.