EFFECT OF PITUITARY GROWTH SUBSTANCE ON THE DEVELOPMENT OF RATS THYROIDECTOMIZED AT BIRTH¹

Abstract

ALTHOUGH both thyroid and pituitary play a part in the normal growth and development of the individual, the pituitary can, under certain circumstances, A. JA. act without the thyroid. Evans, Simpson and Pencharz; (1), also Flower and Evans (2), induced growth in rats thyroidectomised after weaning by injection of AP growth substance. Ossification of epiphyseal lines was accelerated by pituitary growth hormone in thyroidectomised guinea pigs (120–180 gm.) (3). On the other hand, Shelton, Tager and Hoyt (4) found it impossible to cause osseous advancement in a human cretin with pituitary substance alone. In a previous experiment by the author (5) growth was not induced by two pituitary implants daily in rats completely thyroidectomised at birth, although one pituitary implant daily was sufficient to cause growth in animals possessing a thyroid remnant. In that case an interval of 3 to 4 weeks elapsed between thyroidectomy and the beginning of pituitary administration.