Electron Microscopic Study on the Adrenal Medulla of Domestic Fowl

Abstract

An electron microscopic study had been made on the domestic fowl adrenal medulla, from 14 days of incubation to 980 days after hatching. Small pieces of the adrenal gland were fixed for one hour in phosphate-buffered 1% osmium tetroxide. After washing and dehydrating, the tissues were embedded in mixture of 1 part methyl and 4 part butyl methacrylate. Sections, cut with J. U. M. 4 type ultramicrotome, were examined with J. E. M. 4A type electron microscope.1. In the adrenal medulla of domestic fowl two types of medullary cells are found. The author named these cells respectively‘the first type’and‘the second type cell’.2.‘The first type cells’construct the greater part of adrenal medulla. This cell has abundant spherical osmiophilic granules with variable sizes in a relatively opaque back-ground cytoplasm. These granules, seen already in 14 days old chick embryo, are varying in diameter between 40 and 350mμ and with a mean of 146.3mμ in 18 days chick embryo, of 132.9mμ in 980 days old hen. Most of the granules have light halo burying in thickness of 200Å-1μ between the single limiting membrane and the center portion of high electron density. In chick embryo and young chick this halo is generally narrow and in older hen is relatively wide and more variable in thickness.3. In embryo and young chick GOLGI apparatus is recognized apparently. The osmiophilic granules and intermediate forms between the osmiophilic granules and the GOLGI vesicles are much more frequently encountered within GOLGI apparatus. This fact suggests that granule formation may occur within the GOLGI apparatus, and the outer membrane of the granules may originate from GOLGI vesicle. The mitochondria around the GOLGI apparatus may take also some parts in the formation of granules in the GOLGI apparatus. From above mentioned facts, it is concluded that the osmiophilic granules are not cell organoids but secretory inclusions.4. In old hen, there are undifferentiated large osmiophilic droplets with various sizes and irregular structures. Some of these may be originated from catechol amine or others from fatty infiltration.5. The shape of mitochondria with a well known inner structure is genrally elliptical, but sometimes horse, ring or long filamentous. These are more frequently seen around the GOLGI apparatus.6.‘The second type cell’contains not spherical but polymorphic or comma shaped osmiophilic granules. These cells are scattered scarecely among the first type cells. In this type cell, outer membranes of the osmiophilic granules are lost or broken more frequently than those in the first type cells.7. The sinusoid capillary is limited by the endothelial lining. Between the endothelium and the parenchymal cell membrane there is a perisinusoidal space which communicates with inter parenchymal-cell space.8. Between the medullary cell columns there is the bundle of unmyelinated nerve fibers invested by a SCHWANN'S cell. In the nerve endings connected with medullary cell a typical vesicular component consisting of the synaptic vesicles is observed.