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Stereological estimation of the total number of neurons in the asexually dividing tetrathyridium of Mesocestoides corti
Published online by Cambridge University Press: 06 April 2009
Summary
Fifty tetrathyridia of Mesocestoides corti showing various degrees of scolex fission during asexual multiplication were subjected to estimation of the total number of neurons in the central ganglia, using a ‘fractionator’ designed sampling scheme on every 10th Historesin section through the specimen. Neurons were stained with Cresyl fast violet and viewed by transmission light microscopy. Cells were only counted if a nucleolus was present. The animals were divided into groups according to their stage in the asexual reproduction process indicated by head shape and sucker number. Animals which had a narrow head with 4 suckers contained about 250 neurons. As their heads became wider, in preparation for fission, neurons were overproduced by up to 5-fold. As additional suckers were developed (8 in total), neurons were reduced to about 500. Finally, when the animals had 2 clearly discernible heads, with 4 suckers on each, the total number of neurons (per head) was again approximately 250. As the heads became wider again, neuron over-production recommenced. Exceptionally shaped animals with an X- or T-shaped single head were observed. These results suggest that there is a preparatory stage for neuronal regeneration, during which the basic population of neurons is about 250. This is followed by neuron over-production followed by a selective cell death of neurons which occurred during asexual multiplication. Another cycle for neuronal regeneration can occur before an animal completes its fission process.
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- Copyright © Cambridge University Press 1993
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