The fine structure of sickled hemoglobin in situ.

E CRUMPLING of disc-shaped erythrocytes into bizarre forms is considered the basic pathological feature of sickle cell anemia.1 Several investigators have established that erythrocyte sickling is due to intracellular precipitation of deoxygenated sickle hemoglobin ( Hb S ).2.T A recent ultrastructural study by Murayarna identified the presence of tubular rods of Hb S in whole mount preparations of sickle cell hemolysates.8 From this observation, he theorized that crumpling of sickle cells is caused by aggregation of Hb S molecules into microtubules. Electron microscopic investigations of plastic embedded sickled ervthrocytes,9’#{176} however, have not demonstrated dense tubular rods in intact red cells similar to those observed in hemolysates by Murayama. The present study was initiated for the purpose of clarifying the fine structural appearance of sickled hemoglobin in situ. During the investigation, it was found that glutaraldehyde is not only an excellent fixative for preserving Hb S in situ, but also appears to promote the sickling phenomenon. The results indicate that dense rods similar to those found in hemolysates do occur in the cytoplasm of sickled erythrocytes, and the parallel orientation of the rods appears instrumental in crumpling erythrocytes containing Hb S.