抄録
The adrenal glands of the Wistar-Imamichi rats during the postnatal development were investigated histologically. The zona glomerulosa in the newborns and infantiles up to the 5th day of birth had a fasciculo-arcuata appearance. The provisional, transitional zone was formed on the 15th day in females and on the 21st day in males. Subsequently, the zona intermedia appeared on the 27th day in females and on the 30th day in males, but this zone was, thereafter, interrupted by penetration of cell-strands descending to the zona fasciculata. The frequency of interruption is higher in the adult female than in the adult male. In the adult Donryu rat this zone is always recognizable and distinctive. The whole width of the zona intermedia was for the first time demonstrated electron microscopically in the two different strains. The submicroscopical characteristics of the cortical cells may aid in the distinction of different zones. The mitochondria, smooth canalicular endoplasmic reticula (ER) and fat droplets have their own features peculiar to each zone. The mitochondria apparently consists of the cristae, tubular cristae, tubuli, tubulovesicles, vesicles and lamellar structures in order from the superficial area to the deeper area of the cortex. The glomerulosa cells are marked by an accumulation of smooth canalicular ER constituting a network. These ER grow large in diameter as the cortical cells descend to the zona reticularis, and finally present an appearance of a vesicle. The confluence of anastomosing ER may be the site of initial fat deposition. The large fat droplets may have been derived from small fat deposits in these confluences. The mitochondria in the zona reticularis were degenerated into lamellar structures, in which fat substance was deposited. Some fat droplets in the inner zone of the cortex are of a mitochondrial origin and may give a degenerative sign. There was evidence that the longitudinal strands passing through the interruptions of the zona intermedia make a combination of the glomerular and fascicular zones. The perpendicular transformation of the cortical cells was suggested by the present observations on the submicroscopical structures of the three different zones in the cortex.
