Fusiform erythrocytes resembling sickle cells in angora goats: observations on osmotic and mechanical fragilities and reversal of cell shape during anaemia.

Osmotic and mechanical fragilities of erythrocytes were determined for seven goats having 3.4-71 per cent fusiform erythrocytes. The osmotic fragility was related to the erythrocyte shape in that the osmotic resistance was considerably higher for bloods containing more than 26 per cent fusiform erythrocytes. A decrease in the proportion of fusiform erythrocytes in the same goats was related to an increase in the osmotic fragility. Anaemia was induced in two goats by removal of 200-400 ml of blood at three or four day intervals for eight weeks. Red cell values decreased by 28-43 per cent within three weeks, but further bleeding produced either no or less (0-21 per cent) reductions in these values. Slight reticulocytosis was seen during the anaemic phase and there was a concomitant increase in the mean corpuscular volume and mean corpuscular haemoglobin values. Reticulocytosis diminished before the start of recovery from anaemia and disappeared during the recovery phase. The most significant finding was the change in the erythrocyte morphology during production of and recovery from anaemia. The development of anaemia was associated with a gradual reduction in the proportion of fusiform erythrocytes or discoid cells and simultaneous increase in the proportion of erythrocytes exhibiting distinct poikilocytosis. Recovery from the anaemia was rapid (within five weeks), but reversal of the erythrocyte shape took several months. Severe blood loss anaemia in the goat is known to induce synthesis of haemoglobin C, and in these anaemic goats formation of a new haemoglobin, most likely haemoglobin C, was demonstrated by electrophoretic and column chromatographic analyses. It was concluded that the formation of haemoglobin C was responsible for the morphological changes in the erythrocytes.