Abstract
Recent work by Herring 1 has shown that complete removal of the thyroid in rabbits, cats and dogs is followed by definite histological changes in the pituitary body. A greatly increased production of colloid material by the cells of the pars intermedia was indicated. Accumulations of colloid were observed in the nervous portion of the posterior lobe and in the laminæ forming the floor of the third ventricle whence it appeared to find its way between the ependyma cells into the infundibular recess and brain ventricles.
It is believed by many that the iodine-containing substance — the so-called iodothyrin or thyroiodin — is the active substance of the thyroid gland. Reid Hunt states that the physiological activity of the thyroid varies directly with the percentage of iodine which it contains. According to Baumann, Halliburton 2 and others the pituitary yields no iodine. Gideon Wells, 3 from an analysis of fourteen normal human pituitaries, found an average amount of 0.0036 milligram of iodine for each gland — about one fiftieth of the quantity found in the thyroid. Ox pituitary obtained from Armour and Co. tested by Hunter's method gave no iodine and sheep's pituitary from the Ithaca slaughter house yielded only a trace.
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