Fusion of erythrolysosomes in epithelial cells of the sheep placenta.

In trophoblastic epithelial cells of the sheep placenta the breakdown of erythrocytes within complex erythrolysosomes was studied at the ultrastructural level. It was found that the formation of complex erythrolysosomes containing from two to several erythrocytes as a result of fusion of erythrolysosomes within the epithelial cells was a common occurrence when the epithelial cells engulfed a large number of erythrocytes. The erythrocytes enclosed in complex erythrolysosomes appear to be either in the same or in different stages of hemolysis. In the process of breakdown of erythrocytes within complex erythrolysosomes five successive stages of hemolysis could be distinguished. Acid phosphatase activity was demonstrated in the complex erythrolysosomes and appeared to be located in the angular interspaces between the erythrocytes and the lysosomal membrane. The fragmentation of complex erythrolysosomes with formation of small hemoglobin-containing lysosomes also occurred. The fusion of erythrolysosomes with formation of complex erythrolysosomes can be considered as an additional mechanism in the process of erythrocyte breakdown in the epithelial cells of the sheep placenta.