A new type of cell death, the protruded type, observed in the adrenal gland of normal rats

Apart from apoptosis, a type of parenchymal cell death by the cell protruding into the capillary lumen was observed in the adrenal gland of normal Sprague-Dawley rats. Ultrathin sections were prepared in the conventional manner and were examined by electron microscopy. The protruded cells (p-cells) had the electron lucent cytoplasm and the p-cells with ruptured cell membranes were observed in the capillaries. The egress of p-cells was either through the endothelial gaps, or following the rupture of capillary endothelia. The cytoplasmic matrices of the dying p-cells were seen to scatter in the capillary lumen where the nuclei, mitochondria and granules remained morphologically intact. The p-cells were seen in the capillaries of medulla, but restricted to those of zona reticularis in the cortex.