THE FINE STRUCTURE OF THE INTERRENAL CELLS OF THE BROWN PELICAN

Abstract

The interrenal cells of brown pelican fledglings have been investigated with the electron microscope. Between the endothelium and the parenchymal cell, located in the subendothelial space, numerous reticular fibers were found which have not been described in the adrenal gland of any other species. Although the cells are arranged into formations similar to a zona glomerulosa, zona fasciculata, and zona reticularis, no fine structural differences were observed among these zones comparable to that found in mammalia, so that interrenal tissue consisted of a single cell type. The fine structural characteristics of the interrenal cells were generally similar to those of other species in that they possessed mitochondria with tubular internal structure, numerous lipid droplets of varying complexity, small vesicles bounded by agranular membranes, a small Golgi apparatus and little or no granule studded endoplasmic reticulum. The center of the cell cords from which the columnar cells radiate outward showed a space in which a fine flocculent material was uniformly dispersed. The varied appearance of lipid droplets was discussed.