Fractionation of the avian erythrocyte: An ultrastructural study

Abstract

A method is described for the preparation of hemoglobin-depleted erythrocyte ghosts from chicken and turkey erythrocytes by osmotic hemolysis followed by repeated washing. These ghosts retain the shape of the intact erythrocyte and also the cell nucleus. Electron microscopy has shown the presence of mitochondria and the outer nuclear membrane, both of which tend to be hidden when the hemoglobin is present. Also, fibrils have been observed surrounding the mitochondria and nuclei. Fibrils appear to pass between the plasma membrane, and these organelles may provide an anchorage mechanism, particularly for the nucleus, which always occupies a central position within the ghost as it does in the intact erythrocyte. By means of a controlled ultrasonication treatment, it has been possible to disrupt the plasma membrane of the avian erythrocyte ghost while leaving the nucleus intact. A nuclear fraction and a crude membrane fraction which contains mitochondrial and plasma membrane fragments have been otained. Most of the nuclei do not have a continuous outer nuclear membrane, which thus appears to be an extremely frail structure. Some of the plasma membrane and mitochondrial fragments had fibrils still attached. The results are discussed in relation to the ultrastructure of the avian erythrocyte. In particular, possible functions of the hitherto unknown fibrillar structures are expanded upon in relation to the positioning of the cell nucleus and the cell shape.