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A glial cell subtype, previously classified as a beta astrocyte on the basis of its ultrastructural and radiobiological characteristics, has now been shown to represent the most mitotically active component of the glial population in the grey matter of the cerebral cortex of the young adult rat. The labelling index of 0.83% was evaluated using semithin… (More)
Two leukemogenic viral populations were derived from a radiation leukemia virus of the C57BL mouse. One (FB), in which only B-tropic virus could be detected, was obtained in vivo by serial passage of cell-free extract in newborn rats. The second (3C), a complex containing at least B-tropic and xenotropic viruses, was produced in vitro by a permanent cell… (More)
The depth of the cingulum bundle, a myelinated substructure of the corpus callosum was found to represent a sensitive indicator of exposure to X-irradiation in utero at dose levels as low as 20 cGy. In such conditions, the origin of the anatomical damage is probably to be found in a disordered sequence of morphogenetic events rather than in mitotic cell… (More)
Pregnant rats were fed a diet containing 1.8% lead acetate for 8 days before delivery until the young were 3 month old. The density of the cerebral cortex capillaries of the infant rats and their convolution rate were studied morphometrically and noted to increase significantly according to the duration of lead treatment, as demonstrated by two-way analysis… (More)
Autografts from spontaneous cancers of mice when replanted into areas previously exposed to an erythema dose of x-rays, failed to grow in the majority of instances (71.4 per cent), while similar grafts inoculated into untreated areas grew in a large proportion of the animals (83.6 per cent). Autografts of spontaneous cancer, established and growing in the… (More)
The three types of glial cells (astrocytes, oligodendrocytes and microglia) were counted at 2 different ages in normal and lead intoxicated animals (on a 0.5% Pb2+ diet) and were found to vary differently with respect to age and lead treatment. Satellisation of nerve cells by glia also displays a different pattern : whereas usually at 3 month age, the… (More)
This communication deals with an ultrastructural assay of certain quantitative brain parameters susceptible to be modified during heavy metal intoxication. It particularly focusses on the changes in the populations of glial cells which appear as a most sensitive morphological indicator of brain poisoning.