Splenomegaly and haematologic disorders of the Gunn rat.

Abstract

Summary. Erythrocyte values, leucocyte counts, haemoglobin components and erythropoietin levels were determined in Wistar and Gunn rats. Spleen and bone marrow examinations were also performed. Erythrocyte values and leucocyte counts in Gunn rats were lower than in Wistar rats. Females of both strains of rats showed lower haematocrit values, haemoglobin concentrations, erythrocyte counts, and erythropoietin levels than did the males. Female Gunn rats also had leucopenia when compared with the males. The leucopenia disappeared after castration. The erythrocyte abnormalities were particularly marked in homozygous female Gunn rats which manifested anaemia, shortened erythrocyte survival time and splenomegaly. After splenectomy and/or ovariectomy, the erythrocyte survival time became normal and the anaemia improved. However, ovariectomy alone did not influence the splenomegaly nor the enhanced splenic sequestration of erythrocytes. Microscopic examination of the bone marrow of Gunn rats revealed normal overall cellularity. In contrast, hyperplasia of the white and red pulp was observed in the spleens of Gunn rats of both sexes. These findings suggest that the anaemia of homozygous female Gunn rats is caused by enhanced sequestration of erythrocytes in the spleen and by a possible disturbance of oestrogen metabolism.