We evaluated the relationship among proliferation, death and migration of granule cells in lobules VI-VIII of vermis, in comparison with lobule III, during cerebellar development. To this aim, a single injection of cisplatin, i.e., a cytostatic agent that is known to induce death of proliferating granule cells, was given to 10-day-old rats. Histochemical markers of proliferating (PCNA immunoreaction) and apoptotic (TUNEL staining) cells were used; the variations of the external granular layer (EGL) thickness were evaluated in parallel. After PCNA and TUNEL reactions, evident changes of the whole EGL were found on PD11 (1 day after treatment), when a reduction of the thickness of this layer was found in treated rats, mainly in consequence of the high number of apoptotic cells in all the cerebellar lobules. On PD17 (7 days after treatment), a thick layer of proliferating cells was observed in lobules VI-VIII of treated rats, while the peculiar pattern of the normal development showed a thin EGL. At the same time, in treated rats, the number of apoptotic cells in EGL was low. In all developmental stages of treated rats, after GFAP immunoreaction, glial fibers appeared twisted, thickened, and with an irregular course; intensely labeled end-feet were present. The damage of radial glia suggests an alteration of migratory processes of granule cells, which is also evidenced by the decreased thickness of the premigratory zone of the EGL. Injured radial glia fibers were restricted to lobules VI-VIII and they persisted at PD30, leading to the presence of ectopic granule cells in the molecular layer, as we previously described.

No abstract

In the present research encephalons were considered from an early larval stage of the frog (Sana klepton esculentd). The animals were divided into two groups, i.e., control (CL) and contaminated (CT) frogs, on the basis of chemical analyses. Proliferating activity was evaluated in brain sections after immunoreaction with an anti-PCNA (Proliferating Cell Nuclear Antigen) antibody. The results showed the presence of many immunolabelled cell nuclei in the ventricular walls of the encephalic vesicles, but the patterns appeared changed in the CTs. Moreover, CT tadpoles had Trematoda larvae inside the brain ventricles. The findings showed that amphibian developing nervous tissue is vulnerable to environmental cytotoxic agents and confirmed that amphibians are excellent biomonitoring indicators of water.

No abstract