Abstract
It has been known for nearly a century 1 that individuals and animals with endemic goiter or cretinism have hypertrophy of the anterior pituitary. In man pituitary weights up to 3 gm. have been recorded, while in rabbits of approximately 2 kg. body weight with large parenchymatous goiters we have observed pituitary weights of 0.070 gm., whereas our normal average weight of the pituitary of rabbits of this size is 0.020–0.022 gm. Rogowitsch 2 first demonstrated that the anterior pituitary cells of rabbits underwent hypertrophy following thyroidectomy, an observation which has been confirmed by most subsequent observers for many species of mammals including man, as well as lower orders (amphibians, reptiles). Pituitary hypertrophy following thyroidectomy is most pronounced in young rabbits and may be overlooked in old adults.
During the past 4 years we have readily produced large parenchymatous goiters in prepuberal rabbits by maintaining them on a diet of alfalfa hay of low iodine content, whole oats, tap water and the daily injection of methyl cyanide up to 0.1 cc. in 20% solution intramuscularly. This material has made it possible to compare in the same breeds of rabbits under similar environmental conditions the hypertrophic changes in the anterior pituitary associated with parenchymatous goiter with similar changes following thyroidectomy.
As Rogowitsch has pointed out, all the cells of the anterior pituitary undergo hypertrophy following thyroidectomy and coincident with this there is a progressive relative increase in the chromophobic and a decrease in the stainable acidophilic cells, which in the rabbit attains its maximum between the 30th and 60th day. Contrary to the opinion expressed by Bryant, 3 we believe that the apparent increase in chromophobic cells is due to a degranulation of acidophilic cells.
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