Effects of transplantation on mouse adrenal chromaffin cells.

The effects of long-term transplantation on the ultrastructure of adrenaline- and noradrenaline-storing cells from the adrenal medulla were determined using morphometric methods. Mouse adrenal medulla were freed from the adrenal cortex and grafted into the occipital cortex of the brain. Two types of chromaffin cells were identified by electron microscopy in grafts fixed with glutaraldehyde and osmium tetroxide. Noradrenaline-type cells were predominant and formed 70-80% of the surviving population of grafted chromaffin cells. A minority of the chromaffin cells contained medium-sized granules (140-210 nm in diameter) (medium granule cell; MGC) with finely granular moderately electron dense cores. Morphometric analysis of noradrenaline phenotype cells and MGC cells in transplants showed no significant differences compared with the noradrenaline-storing cells of normal adrenal glands. In contrast, noradrenaline-type cells and MGC cells in the grafts had areas of secretory vesicles which were significantly (P less than 0.01) larger and areas of rough endoplasmic reticulum which were significantly (P less than 0.01) smaller than those of the adrenaline-storing cells of normal adrenal glands. It was concluded that long-term transplantation caused no degenerative changes in the ultrastructure of mouse adrenal chromaffin cells.