Abstract
Representative sections from the motor cortex, thalamus, midbrain, cerebellum, medulla oblongata and cervical enlargement of the spinal cord, from each of five cretin lambs and two cretin goats were studied microscopically. A modification of Nissl's method was employed. Comparable preparations from three normal animals of the same sex and age (twins of three experimental animals) furnished the control material. The primary purpose of this series of investigations was to determine the nature and course of the nerve cell changes in the central nervous system following the experimental removal of the thyroid glands, and to attempt to correlate these findings with the well known symptoms of athyreosis, many of which are referable to central origin.
It was further desired to compare the nerve cell pictures presented in these cases with those from pathological conditions of quite different etiology and symptomatology in order to determine more fully the nature and degree of specificity of the reaction. To this end the affection of parathyroid tetany was selected, almost the antithesis of the first named condition. If chromatolysis follows in the latter event where neuromuscular activity is frequently at its maximum, should we expect to find a piling up of the extranuclear chromatin in the former where the symptoms are so strikingly opposite in character? Nissl preparations were made from the brains and spinal cords of thirteen dogs in which tetany had been induced experimentally. These were taken from the same levels as described above for the cretin animals.
For further analysis the comparison was extended to cell changes in the central nervous system as a result of functional activity. Fatigue was induced in sixteen white rats by forcing them to swim in a tank of warm water (body temperature) for periods varying from fifteen minutes to six hours.
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