Ultrastructure of Sickled Deer Erythrocytes. I. The Typical Crescent and Holly Leaf Forms

The typical crescent and holly leaf forms of sickled erythrocytes from white-tailed deer were examined by transmission electron microscopy. These cellular aberrations were induced in those animals which are homozygous for the β³-chain and are reversibly related to elevations of pH and P_OO2. The internal structure of the typically sickled cell was organized into polymerized aggregates. At very high magnification, cross-sections of the cells revealed microtubules, with a diameter of 160-190 Å, which were compared to those which have been described in human sickle cells. The tubules beneath the plasmalemma or extending into protruding spicules were more or less parallel and oriented in a single direction, whereas the aggregates in the remainder of the cell cytoplasm were randomly dispersed. In view of the association of the sickling of deer erythrocytes with a specific hemoglobin β-chain and the marked similarity of the internal architecture of these cells to human sickle cells, the deer erythrocytes provide a model for hemoglobin polymerization which may lead to insights that are applicable to the human condition.