Abstract
In studies on compensatory hypertrophy following partial thyroidectomy, Loeb 1 has shown that feeding potassium iodide stimulates regenerative activity while anterior pituitary substance prevents hypertrophy and produces a hard colloid and flattening of the acinar cells. The change induced by potassium iodide in the normal intact thyroid has recently also been studied and a method devised for determining, in a quantitative manner, the proliferative activity by estimating the total number of mitoses in the thyroid gland at any given time 2 , 3 .
These experiments were undertaken to study the effect of combined feeding of these 2 substances and to determine whether or not the inhibiting action of pituitary would render the thyroid unresponsive to the stimulating influence of potassium iodide. If complete physiological neutralization of the stimulating influence of potassium iodide and of the depressing action of pituitary should take place in animals fed with these substances, the thyroid should remain unaltered, but if one were dominant the degree of its influence could be estimated by the mitotic activity of the gland.
Three series of experiments were carried out using in all 45 guinea pigs. They were divided into 4 groups (1) animals fed KI, each receiving 0.05 gm. daily; (2) those fed one 5 grain tablet of anterior pituitary substance (Armour & Go.) every day; (3) those on combined feeding receiving daily both 5 grain pituitary tablet and the 0.05 gm. pill of Kl. (4) Control animals. One series consisting of 5 animal in each group were fed for 20 days; the other 2 series were both fed for 15 days.
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