Perisinusoidal cells in a three-dimensional organization of the adrenal cortex in the monkey.

The adrenal cortex in the macaque monkey was examined under the SEM and TEM to elucidate the surface fine structure of perisinusoidal cells in a three-dimensional organization of the cortex. Parenchymal cells in polyhedral form were arranged in acini in the zona glomerulosa, or in the laminae of closely stacked cells in the zona fasciculata and reticularis. Those acini and laminae were accompanied by sinusoids lined only with an endothelium. Endothelial cells were composed of a protruded perikaryon and a thin layer of peripheral cytoplasm in sieve plates with numerous fenestrations. The perikaryon was sometimes equipped with groups of fenestrated disc-like protrusions. Fine collagen fibrils were distributed in the perisinusoidal space, which was a continuous, slit-like lacune between the endothelial and parenchymal cells. In the perisinusoidal space or intercellular spaces among parenchymal cells were seen two types of perisinusoidal cells: the stellate interstitial cells with several spiny, or attenuated processes entangled with collagen fibrils, and the monstrous wandering cells usually associated with pseudopodia-like processes. The cytoplasm of the interstitial cells showed a structure similar to that of fibroblasts, and contained small numbers of lipid droplets. Intravenously injected chicken blood cells were phagocytized by macrophages on the sinusoidal lining. The fine cytological structure of the macrophages was almost the same as that of the wandering cells. The present findings suggest that the interstitial cells are fibroblastic in nature and belong to the vitamin-A storing cell system, and that the wandering cells are macrophages derived from hematogenous monocytes.