Dejstvo berilijuma na morfogenezu

Abstract

Considering the antimitotical and antienzymatical characteristic of berryllium, the authors tested to investigate the effect of beryliium on the grovvth and metamorphosis of tadpoles. In the expcriment there were used tadpoles of the kind BUFO VULGARIS, of different age, divided into groups, with equal number of both experimental and control tadpoles. The experiments were performed in the months of May ond June 1953. by exposing the tadpoles to the effect of M/1000 and M/1000 of beryllium nitrate solution, being changed every day. The aquariums, which were on a white base, were cleaned daily. Food was uniform: cooked spinach.

A. Results of morphologic-physiological character
1. Tadpoles I. group. — Experiment starte d V. 1. 1953; number of tadpoles: 60; age: 30 days; beryllium nitrate concentration: M/1000.

The fifth day the experimental tadpoles are found to be smaller than the Controls, eating less, mooving lazier, this appearing more and more evident, so that after a month involutive-regressive changes conceming siže and weight reach the maximum, without any sings of metamorphosis, which meanwhile comes to an end in the control tadpoles (fig. 1, graph. 1). An stopping the application of beryllium-nitrate, the grovvth proceeds and the metamorphosis appears. ACTH accelerate morphogenesis of the same tadpoles.

2. Tadpoles II group. — Experiment started: V. 16. 1953. number tadpoles: 60; age: 40 days (posterior extremities acccentuated in the 7th stage after DELSOL); beryllium-nitrate concentration: M/1000

The results are identical with those of the preceeding group (fig. 2, graph. 2).
3. Tadpoles IH. group. — Beginning of the experiment: V. 21. 1953; number of tadpoles: 60; age: 58 days (posterior extremities are in the 10th stage after DELSOL); beryllium-nitrate concentratlon: M/1000

The tadpoles are mobile and eat like the Controls, but growing slower, metamorphosing slovver. Already developed frogs are smaller and ligther than, the Controls (fig. 3, graph. 3).

4. Tadpoles IV. group. — Beginning of experiment: V. 21. 1953; numbsr of tadpoles: 60; age: 35 days; beryllium-salt concenti'ation: M/10000

Mobility and voracity well saved, growth and metamorphosis are happening considerably slower tan in the Controls. Experimental frogs smaller than the Controls (fig. 4, graph. 4).

B. Results of histo-embryological character.

1. Hypophysis. — Groups of cells, building the hypophysis, remain in the embrional stage in tadpoles of I and II group, tili in the control tadpoles there may be differentiated chromophobe and chromophil cells, besides signs of evident vascularisation.

2. Thyroid gland. — Atrophy of thyroid gland,. not quite surpassing the volume of one follicle of the experimential glandular parenchyma in tadpoles of group I and II, with endothelioidal epithelium (fig. 5). In tadpoles of group IV, thyroid gland shows nuclear polymorphism and lower epithelium than i the control (fig. 6).

3. Suprarenal glandular tissue. — The suprarenal blasthema consists of cells, which remained in embrional stage, serried in form of a ribbon against the mesonephros.

4. Branchial braids. — The extension and branching of the branchial braids, covered vith higher and richer epithelium in cells; infiltration of histiocytar cells in the stroma (fig. 7, 8).

5. Liver. — Parenchymatous degeneration and necrosis of the trabeculas in the group I and n, vacuolisation in group IV (fig. 9); mobilisation of Kupffer’s cells (signs of hyperplasia).

6. Mesenchyme. — Sings of hypoplasia (fig. 10).

7. Developement of extremities. — Blocking in histogenesis of the buds of the extremities, reduced to tissue, made from densely congested mesenchymatous cells, without signs of chondrogesis and osteogenesis, as in the Controls (fig. 11).

C. Results of physicochemical character.

The medium wherein the tadpoles were livving, included beryllium carbonate in form of sediment and beryllium-ions. Tadpoles metabolites did not influence the change of value of pH center (gra­ph. 5, 6, 7). In the inorganic rest of experimental tadpoles there has been established the presence of beryllium (spectral analysis, fig. 12). In those however which after 20-days of beryllium effect, were kept 10 days without treating, beryllium could not be found in their inorganic residue.

D. Contemplation of results obtained 

In a discussion of the results obtained, the authors call atention to the variabillity of tissue reactivity in the ontogenesis, due to its constant qualitative change, which migth account for the fact that the same cencentration of beryllium acts dufferently upon younger and elder forms of tadpoles. At the same time the authors emphazise the changes in the endocrine system with particular regard to the inhibition of somatotropical and thyreotropical function of the hypophyseal anterior lobe and effect of diencephalon in connection with the proliferating and resorptive phase of metamorphosis.

E. Conclusions

1. In a cencentration of M/1000 beryllium has an inhibitory effect upon the growth and hinders the metamorphosis of tadpoles, which were not under metamorphosis before the beginning of the experiment. However in tadpoles, exposed to the effect of beryllium during metamorphosis, the growth and metamorphosis take place at a slower rate.

2. The concentration of beryllium M/10000 inhibits the growth
and metamorphosis.

3. The effect of beryllium on the growth and metamorphosis is of a reversiBle character.

4. The valne of pH solution showed no essentially differences. The specific effect of beryllium appears in the mobilisation of Kupffer’s cells, invasion of branchial stroma by histiocytar elements and by hypoplasia of the mesenchyme.

6. The neuro-endocrine factors, đominating in the morphogenesis (hypothalamo-hypophyseal complex, glandula thyreoidea) actively participate in the determinism of beryllium’effect upon growth and metamorphosis.