Distribution of Ascorbic Acid (vitamin. C) in cells and tissues of the Developing Chick.
Authors: A. Barnett S. , Bourne G. 
Published: April 2021

ABSTRACT
1. The distribution of ascorbic acid (vitamin C) in the cells and tissues of chick embryos, from the fourth day of incubation to 2 days after hatching, has been studied by the acid silver nitrate method.
2. Mesenchymatous cells show a reaction when undergoing histo-differentiation into cartilage, bone, muscle, dermis, vitreous humour, adrenal cortex, meninges. Differentiated cartilage cells do not contain ascorbic acid except in areas of proliferation ; the cartilaginous matrix may contain it where the cartilage is about to be replaced by bone. Osteoblasts show no reaction at first, a slight reaction when they become surrounded by calcified tissue, and in some cases a strong reaction in older bone. Ascorbic acid is associated with the ‘osteogenic’ fibres immediately before calcification, and is also present in newly calcified trabeculae.
3. In blood ascorbic acid is present in erythrocytes and plasma ; evidence is presented for the view that it accumulates in the older erythrocytes. Cells resembling histiocytes have been observed in muscle, containing high concentrations; no other leucocytes have been observed to show a reaction.
4. Liver shows a strong diffuse reaction in early embryos, but none at all after the tenth day. At the latter age ascorbic acid has been detected in a localized area of cytoplasm which appears to be the Golgi substance.
5. The thyroid shows no reaction at the tenth day, or after hatching, but has been seen to give a reaction at the twelfth day.
6. Various epithelia of the organs of special sense, and of the alimentary canal, contain ascorbic acid.
7. The adrenal, both cortex and medulla, first shows a reaction at the twelfth day; by the fourteenth day typical distributions appear, though the amount of ascorbic acid present continues to increase after that age. The reaction shown by the medullary cells is much stronger than that shown by the cortical elements, a reversal of the condition in the mammalian adrenal.
8. Ascorbic acid was not detected in the testis. In the ovary it appears at the fourteenth day, in a very restricted area of the cytoplasm of certain large cells in the cortex ; at later ages the distribution is similar, but the impregnated area in each cell is larger. The cells concerned are believed to be the germ-cells.
9. The mesonephros contains ascorbic acid from the fifth to the sixteenth days in the tubule cells, the glomeruli, and the lumina of the tubules. In the tubule epithelia the deposit may be localized at one pole of the cell. The metanephros begins to show a reaction at the twelfth day ; here, too, the tubule cells frequently have a deposit at one pole.
10. In the cells of the central nervous system ascorbic acid may be localized in a small area near the nucleus (probably the Golgi material), round the whole of the nuclear surface, or in the axon and axon hillock ; or it may be diffusely distributed through the cytoplasm. A reaction is shown at the fourth day, especially in the axons of certain cells of the brain and spinal cord ; later, localization in the Golgi substance becomes very general in most parts of the brain and cord. A reaction is also shown in ganglion cells, the meninges, and the choroid plexuses. The specific distributions in the principle parts of the central nervous system are described.
11. Results are discussed in the sections on each organ or tissue. In the general discussion it is pointed out that the observations described are concordant with the view that ascorbic acid is frequently localized in the Golgi material. On the other hand, the evidence is that there is no specific relation with the ‘chondriome’ in the embryonic cells of the fowl. The rôle of ascorbic acid in development is also briefly discussed.