The effect of vitamin A on skeletal tissue cultivated in vitro / by Honor B. Fell and E. Mellanby.

  • Fell, Honor B.
Date:
[1951?]
Catalogue details

Licence: In copyright

Credit: The effect of vitamin A on skeletal tissue cultivated in vitro / by Honor B. Fell and E. Mellanby. Source: Wellcome Collection.

    3/4
    [From the Proceedings of the Physiological Society, 19 May 1951.] Journal Physiology, Vol. 114. The effect of vitamin A on skeletal tissue cultivated in vitro. By Honob B. Fell, Strangeways Research Laboratory, Cambridge, and E. Mellanby, Nutrition Building, National Institute for Medical Research, Mill Hill, London The object of this study was to see whether hyper- and hypovitaminosis A acted directly on skeletal tissue grown under the simplified conditions of tissue culture, and if so, what the effects were. The following points will be demon¬ strated : Hypervitaminosis A (1) In one series of experiments, the rudiments of the limb-bones were removed from 6-day chick embryos; at this stage the limb-skeleton consists of very early, unossified cartilage. The cartilages were cultivated by the watch-glass method; one of each pair was placed in normal medium (3 parts plasma : 1 part embryo extract) and the other in medium containing about 1400 i.u./lOO ml. of vitamin A. For the first 2-3 days the two sets of explants grew equally well, the diaphysial cartilage cells hypertrophied and periosteal bone was formed, but the experimental rudiments were more slender than their controls. After 4-7 days’ cultivation, the bones subjected to hyper- vitaminosis A became rather flabby, a constriction appeared at the junctions of the shaft with the epiphyses which finally were completely cut off from the diaphysis, and the rudiments began to shrink; the soft tissue surrounding the cartilage continued to grow actively. The controls remained normal and often trebled their length in a week. (2) The limb-bones of late foetal mice were treated in the same way. These rudiments were well developed when explanted, with a stout shaft of bone containing marrow, and large cartilaginous ends, but they were very susceptible to the action of hypervitaminosis A. After 4 days’ cultivation in a medium containing about 2000 i.u./lOO ml. of vitamin A, the cartilaginous ends began to shrink rapidly, the bone became greatly rarified but the surrounding soft tissue grew profusely. By the 7th day the bone was reduced to a fraction of its original length and after 10 days it had sometimes vanished completely, leaving only a few crumbs of debris scattered in a sheet of actively growing and migrating cells. These changes were not associated with cell degeneration, and the more healthy and active the tissue appeared, the more severe were the effects of the hypervitaminosis. Although the action of excessive vitamin A on these bones is destructive, it depends on the viability of the tissues. Thus heating the bones at 45° C. for 15 min. destroys their power to grow and also their sus¬ ceptibility to excess vitamin A. Heating at 40° C. for 15 min. leaves both actions intact. [p. T. o.