Is atmospheric superoxide vitally necessary? Accelerated death of animals in a quasi-neutral electric atmosphere.

To estimate the necessity of air ions (AIs) as a natural source of atmospheric gaseous superoxide for mammalia the effect of air ion deprivation on mice and rats was investigated. Ambient air deionization inside an experimental acrylic glass cage (AGC) was performed by electrostatic field, built up by acrylic glass surfaces. Under these conditions, four hours after the animals were placed into the AGC, the concentration of negative AIs was not detectable, the concentration of positive ions was (mean +/- SD) 77 +/- 18 ions x cm-3.

Differentiation and programmed cell death in Sa-45 tumour treated with bone inducer.

The relationship between differentiation and concerted cell death was studied using ultrastructural, histochemical and immunochemical methods in solid rat fibrosarcoma Sa-45 grown in the presence of demineralized bone matrix. The control tumour consisted mostly of undifferentiated cells with few poorly or moderately differentiated cells. In the presence of the inducer, cells with a more differentiated pattern appeared in the surrounding area.

Accumulation of DNA within chromocentres of terminally differentiating chick embryo chondrocytes.

Automated television (TV) densitometric technique which allows the recognition and recording of chromatin compartments was applied to the study of chromatin rearrangement during chondrogenesis. Genetically active chondroblasts and inactive definite chondrocytes of E7 chick cartilage model, stained on the imprints for DNA, were a subject for the comparative study. Large chromatin granules with constant morphometric parameters, displaying positive staining for C-heterochromatin and identified as chromocentres, were found to accumulate 30% of cellular DNA, doubling its concentration during chondrogenic maturation.

The hypothalamo-hypophysial system of the lemming Dicrostonyx torquatus Pallas. IV. Influence of experimental animal cooling on the ultrastructure of the hypothalamo-posthypophysial neurosecretory system.

The reaction of the hypothalamo-hypophysial neurosecretory system (HHNS) of lemmings to cold (+4 degrees C) was studied by the method of electron microscopy. The animals were kept in cages with nest, but with no wheel to allow running; in cages with a wheel, but with no nest; in cages with no nest and no wheel. No changes in the HHNS reaction were revealed under cold stimulation, if the animals were not deprived of motor activity (running in a wheel), or could hide in a nest.

The hypothalamo-hypophysial system of the lemming, Dicrostonyx torquatus Pallas. III. Population aspects of neuroendocrine regulation.

The structure and ultrastructure of the following regions of the hypothalamo-hypophysial neurosecretory system (HHNS) in the population cycle of lemming were studied: supraoptic (SON), paraventricular (PVN) and arcuate nuclei (AN), the median eminence (ME) and posterior pituitary (PP). Being compared to the state of endocrine glands and gonads, and the level of reproduction stress in the population cycle of the lemming described earlier, the obtained data revealed a certain regularity. First, at the stages of decrease, increase and in the first period of the stage of population peak the activity of the SON-PP complex and AN is gradually increased.