A Histological Study on the Adrenal Cortex of the Dog

The presence of large numbers of lipid droplets in the cytoplasm of most cortical cells is known as a feature of the adrenal gland of the dog. In the present study histological sections were stained with various selective stains and compared with those stained with sudan black. Lipid staining was performed by the SCHULTZ test, SMITH-DIETRICH reaction, and CIACCIO method. Twelve young dogs of both sexes were employed. Frozen sections of the unstimulated gland contained a large number of sudanophilic lipid droplets of varying size. Inanition of a dog for seven days caused a decrease in sudanophilic lipid droplets of the zonae fasciculata and reticularis. Daily injections of cortisone acetate to starved dogs inhibited the depletion of sudanophilia in the inner zones of the cortex.<br>The intensities of the SCHULTZ test and the SMITH-DIETRICH reaction paralleled the intensity of the sudan stain in every case of the present experiment. The total lipid content determined by the sudan stain was considerably higher than that determined by any of the selective stains.<br>The distribution of lipid droplets demonstrated by the method of CIACCIO was quite different from that of sudanophilia in frozen sections. In normal dogs, CIACCIO-positive lipid (CPL) droplets were presented only in the zona glomerulosa and found in some of the cortical cells bordering a sinusoid. In starved dogs, CPL droplets increased markedly in number and size. Repeated injections of cortisone acetate caused an accumulation of CPL in the zona fasciculata.<br>The amount of CPL in the zona glomerulosa was almost the same as that in the controls.<br>Changes in adrenal lipid were already described by many workers in the rat adrenal cortex given various stimuli. The lipid changes clarified in the present experiment were similar to those observed by previous workers in frozen sections. However, the results of investigation on CPL were peculiar. The CIACCIO method has scarcely been used in the study of adrenal lipid probably due to the general disrepute in which this method has been held. The author is of opinion that is reliable if its technique is carried out strictly.<br>Such peculier changes of CPL as observed in this experiment have not yet been noted.<br>It has been known that the adrenal cortex is characteristically a lipid-poor structure in the hamster and ruminants. It was suggested that the distribution and alteration of lipid in the adrenal cortex were not the same in these animals as in the other animals. The distribution and histochemistry of CPL coincided exactly with those of the lipid which had been reported to be present in lipid-poor adrenals. Accordingly, the CPL detected in this experiment might probably be the same with solitary lipid in lipid-poor adrenals.