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Biomedical subjects

P D Coleman

Publications and source records attributed to P D Coleman.

4 recordsLinked to original sources
PubMed1979

Dendritic growth in the aged human brain and failure of growth in senile dementia.

Golgi-stained dendrites of single randomly chosen layer-II pyramidal neurons in the human parahippocampal gyrus were quantified with a computer-microscope system. In nondemented aged cases (average age, 79.6 years), dendritic trees were more extensive than in adult cases (average age, 51.2), with most of the difference resulting from increases in the number and average length of terminal segments of the dendritic tree. These results provide morphological evidence for plasticity in the mature and aged human brain. In senile dementia (average age, 76.0), dendritic trees were less extensive than in adult brains, largely because their terminal segments were fewer and shorter. Cells with shrunken dendritic trees were found in all brains. These data suggest a model of aging in the central nervous system in which one population of neurons dies and regresses and the other survives and grows. The latter appears to be the dominant population in aging without dementia.

Aged↗
PubMed1977

Complexity of branching dendritic trees: dependence on number of trees per cell and effects of branch loss during sectioning.

We have investigated whether the complexity of dendritic trees is correlated with the number of primary dendrites per neuron (trees per cell). In estimating the average number of branches of centrifugal orders 1-5 per tree we used statistical methods to compensate for loss of parts of trees during sectioning. Limitations of these methods are discussed. Neurons from four populations, stained by the Golgi-Cox method, were examined: stellate cells from layer IV, area 17 of visual cortex, in normal and dark-reared cats; the pyramidal cells from layer V, somatosensory cortex, in two strains of rats. In all four groups of neurons the average number of branches of higher orders (3, 4, 5) per tree tended to be smaller in neurons bearing more trees. Thus all trees from a population of neurons should not be assumed to be equivalent. The decreasin high-order branches per tree tended to offset the increase in number of trees per cell. In three of the four groups these opposed tendencies maintained the average number of high-order branches per neuron nearly independent of the number of trees per cell. Natural selection may have favoured near-constancy in the number of high-order branches to reduce dispersion among neurons of one type in functional input-output rleations.

Animals↗
PubMed1976

A Bodian method for mounted frozen sections.

For application of the Bodian method to frozen sections, cut frozen peripheral nerve or muscle at 10 mum and mount. Fix for 4 days in 18 parts 80% ethanol, 1 part 10% formalin, and 1 part glacial acetic acid. Fix central nervous tissue in the same mixture prior to freezing and sectioning, and after mounting postfix for 4 days. Impregnate by the Bodian procedure. The results equal Bodian stains of paraffin sections. The technique is simple and reliable. The use of 10 mum frozen sections produces little artifact and allows alternate serial sections to be stained with other techniques.

Animals↗