Abstract
The fine structural changes of the adrenal medulla of chick at 1-3 hours after subcutaneous injection of insulin were examined with electron microscope.
1. Osmiophile secretory granules in the medullary cells were remarkably reduced in number, size and electron density; while the white halos around them became larger and round in form.
2. A many of smooth surfaced vacuoles considered as white halos without osmiophile granules appeared in most cells. In these vacuoles fine microgranules, perhaps fundamental components of secretory granules, were diffusely to be seen.
3. Round mitochondria, the cristae of which are disarranged and reduced, were seen in the cytoplasm. But normal long mitochondria, the cristae of which are arranged laminarly, were rare.
4. Sinusoidal endothelium with many pores and the perisinusoidal space lying between endothelium and parenchymal cell became thinner.
5. Sometimes large intercellular spaces with low electron density appeared between these medullary cells.
6. The capillary spaces became denser with fine osmiophilic micro-granules. These were considered as reduced substances related to adrenaline
7. Above-mentioned changes weer considered to be induced by hypersecretion of the cells after injection of insulin.
