The regenerative power of the optic lobe was studied in 70 young metamorphosed specimens of Xenopus laevis. The experimental animals were grouped as follows: Group I: more than 80% of the volume of the optic lobe was removed. Group II: 30% to 50% of the volume of the optic lobe was ablated. Group III: less than 30% of the optic lobe was ablated. The results showed than the regenerative capacity of the midbrain in metamorphosed specimens is very low. Only when the ablation of the optic lobe was inferior...
70% of the tail was removed in larvae of Xenopus laevis at stage 48 (according to Nieuwkoop and Faber) in order to: a) analyze the course of the regeneration process of the spinal cord in the tail; b) accertain the morphogenetic potential of the ependymal cells which replace the spinal cord experimentally removed; c) compare the regeneration capacity of this Anuran with that of the Urodela which is already known. Morphogenetics phenomena noted in the days immediately following the operation are...
Unilateral ablation of the midbrain was performed in 27 tadpoles of Xenopus laevis (Daudin) at stage 47 (according to Nieuwkoop and Faber). Their brain was implanted in the anterior chamber of the eye of adult specimens of Rana esculenta L. and was fixed at 10-20-30 days after the operation. In some cases we observed that the implanted brain displayed a regenerative capacity which, although much less ineffective than in vivo, led to the regeneration of a new mesencephalic wall. In the partially...
Removal of the whole midbrain was performed in larvae of Rana dalmatina at stage 32 and of Rana esculenta at stage 33 (according to Manelli and Margaritora). The results show that the regeneration of the mesencephalon and particularly of the optic tectum is possible also from non-mesencephalic regions and is accomplished by pluripotent elements the determination and differentiation of which take place during the regenerative process.
In a previous paper by one of us (Filoni and Oberti, 1968), the poor regenerative capacity of the optic tectum in adult specimens of Xenopus laevis was reported. The right optic lobe had been removed by suction; since this technique causes connectival proliferation at the healing site, it was decided to repeat the experiment by operating the animals in two different ways to ascertain the effective regenerative power of the midbrain. The right optic lobe of adult Xenopus laevis was removed either...
The regeneration of the midbrain following to the ablation of the right optic lobe has been studied in larvae of Rana esculenta at stage 32 (according to Manelli and Margaritora). The results were in agreement with those previously obtained with other species of Amphibia anoura; they demonstrated that the regenerative process causes the neoformation of an optic lobe which is like that of the control side, both in volume and histological structure.
The experiments in this work were designed to study the regenerative capacity of caudal spinal cord in larval Xenopus laevis at stages near to metamorphosis. 70% of the tail was removed in larval Xenopus laevis at stage 56-57 (acc.to Nieuwkoop and Faber, 1956). The experimental animals were reared in 0.01% solution of PTU (4(6)- Propyl-2-thiouracil) in order to inhibit metamorphosis, and sacrificied after 3-5 months. The results obtained demonstrated that: a) the regenerated spinal cord of the tadpoles...
Lens capsule epithelium fragments were left in the eye of adult specimens of Rana esculenta. The histological data demonstrated that the lens capsule epithelium fragments can form epithelial vescicles where the cells start to divide; afterwards, the cells situated in the posterior part of the vesicle become elongated, differentiating into fibers.
In the present work, tadpoles of Xenopus laevis were submitted to successive removal of 70% of the tail. The structure of the regenerated spinal cord and the evolution of the regenerative process was compared with, those of tadpoles submitted to one amputation. The results obtained demonstrated that: 1) Either after one amputation or after two or three amputations, the regenerative process exhibits the same phases: a) migratory phase, b) multiplicative phase, c) differentialve phase. 2) Either...
The histology of normal and regenerated optic lobes was examined in young specimens of Xenopus laevis by applying the Golgi-Cox method. In the operated animals the unilateral ablation of the optic lobe has been performed at the early larval stages (48-51) and at the later larval stages (55-56), according to Nieuwkoop and Faber. From our observations we drew the following conclusions: 1) The histological features of the optic tectum of Xenopus laevis are essentially similar to those of other Anurans....
Fifty larvae of Xenopus laevis at stage 48 (according to Nieuwkoop and Faber) were submitted to tail amputation. Either 50% or 70% of the tail was cut off. The animals were sacrificed from the 30th to the 40th day after the operation, when they had reached stage 56-57. The study of the regenerated tail demonstrated that the histological structure of the neo-formed spinal cord is very similar to that of control animals, although the volume is clearly reduced. The regenerated spinal cord is constituted...
The effect of X-rays (450 r) upon the distribution of acid phosphatase in the cervical lymphnodes of total body irradiated young mice was studied. Immediately after irradiation the cortex of lymphnodes displayed a higher enzymatic activity than the medulla. The intense enzymatic activity was localised in the lymphatic nodules of lymphnodes, and it was particularly evident in their central germinal. The higher acid phosphatase content observed following X-ray irradiation induced us to presume two...
In order to establish if the antithyroid substance 4(6)-propyl-2-thiouracil (PTU) directly affects the regenerative process of the optic tectum, larval Xenopus laevis at stage 48 (according to Nieuwkoop and Faber, 1956) were submitted to ablation of the right optic lobe and reared in 0.01 % PTU solution. The regenerative process of the optic tectum were compared with controls reared in water. The results obtained demonstrated that the PTU has no direct effect either on the proliferative phase or...
The biological effects of X-rays and sulphur mustard on the thymus of young rats were compared. The results can be summarized as follows: 1) after X-irradiation the thymus presents a remarkably altered histological picture (high percentage of picnotic lymphocytes, mitotic inhibition, alteration of the cortico-medullary boundary) but it has a rather rapid recovery with a maximum of the mitotic activity at the 5th day after irradiation. 2) The treatment with sulphur mustard caused delayed histological...
Skin fragments (6x4 mm) from adult Triturus marmoratus Latr. were grafted on the dorsal side of adult Triturus cristatus carnifex Laur. The recipient newts were divided into four batches: 1) non-treated (control specimens); 2) X-ray irradiated (1250 r); 3) X-ray irradiated (2450 r); 4) X-ray irradiated (2450 r) and injected with a spleen suspension from the donor. From the results it was apparent that: 1) in non-irradiated allografts an early histoincompatibility reaction develops (day 15); 2) the...
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