Some Experimental Biological Uses of the Element Beryllium (Glucinum)

Authors


Abstract

Summary.

1. The quantitatively outstanding effects of beryllium on embryonic development may be correlated with the rarity of this element in nature.

2. Qualitatively the effects are such as may be produced by other chemical agents in appropriate concentration and by other experimental means. The most notable are: exogastrulation, spina-bifida, axial defects in general, hemicephaly and microcephaly.

3. Situs inversus of heart and viscera has not previously been produced in Amphibia by chemical means, but no doubt is part of the general complex of effects.

4. The common action of all reagents would seem to be essentially one of inhibition, acting differentially on different parts of gradients of activity in the embryo.

5. There is evidence for the existence of three main gradients in the embryo, in the three dimensions of space. Two gradients alone cannot explain the organization of the Vertebrate embryo.

6. The form and orientation of the gradients changes during normal development. This is reflected in the complexity of the experimental effects produced.

7. The question of the evolutionary significance of the “mosaic” stage of development is raised.

8. Rhythms in susceptibility to external agents during development are revealed.

9. Examples of dependent and of independent differentiation are noted.

Summary.

1. Beryllium salts have a powerful inhibitory effect on regeneration in Amphibia. No other agent used had a comparable effect, which might indicate the chemical mechanism of the effect.

2. Inhibition of regeneration with beryllium provides a valuable means of investigating the problems of regeneration and growth. The present experiments indicate that :–

(a) A factor produced very locally at the cut surface at the time of operation is largely responsible for regeneration. It is this factor which is so rapidly inactivated by beryllium treatment.

(b) There is evidence of a second factor concerned in regeneration in Amphibia. This appears to emanate along the axis, in the tail.

(c) Partial inhibition affects both rate of regeneration and final size of the regenerate. This supports the indication that regeneration does not depend on a single factor.

(d) Partially inhibited limbs have frequently fewer digits than normal.

(e) The stump of inhibited limb-buds develops as a mosaic (i. e., does not regulate).

(f) Normal powers of regeneration vary considerably in different animals.

(g) The “wound factor” may possibly show affinities with the “organiser” substance of embryological development.

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