“…Many studies have been made of the pathological changes in the blood vessels in human and experimental hypertension both by light [12,15,26,27,30,32,37] and electron microscopy [13,18,23,28,32,34], The rat has dominated the literature as an experimental animal. The in vestigation of hypertensive states, both spontaneous and those induced by renal abnormalities, steroid and salt treatment, adrenal regeneration, aortic stenosis, and drugs, in this species has furnished data elucidating mechanisms of this disease.…”