Analytical color fluorescence electron microscopy of adrenal cortex

The analytical color fluorescence electron microscope (ACFEM) was employed to study rat adrenal gland. The lipid droplets of adrenocortical cells emitted cathodoluminescence (CL) and this spectrum had two peak wavelengths at 320 and 430 nm. Administration of hypocholesterolemic drugs, 17 alpha-ethinyl estradiol and 4-aminopyrazolo pyrimidine, significantly decreased the CL of 320 nm in all three zones of the adrenal cortex. Conversely, in hypophysectomized-rat adrenal cortices, the CL of 320 nm significantly increased and that of 430 nm diminished. In the ACTH-treated group, CL of 320 nm in the zonae fasciculata and reticularis faded up to 2 hours after injection, while that in the zona glomerulosa remained. These results suggest that the CL of 320 nm in adrenocortical cells is derived from cholesterol ester. The CL analysis by the ACFEM in combination with the cryo-scanning electron microscopy method can be an alternative to conventional histochemical technique in simplicity, specificity, and preservation of the ultrastructure.