THE PITUITARY BODY 



tions of the ovary appear to inhibit the secretion of growth- 

 promoting hormone by the pituitary. This behef is further 

 strengthened by the observation of Spencer, D'Amour, and 

 Gustavson that the repeated injection of oestrone into grow- 

 ing rats significantly inhibits growth. Their experiments have 

 been extended by Zondek (1936-37), Billeter (1937), and 

 Freudenberger and Clausen (1937).'* Small doses of oestrone, 

 such as 3 rat-units daily, inhibit the growth of spayed rats 

 so that they may weigh less than non-injected spayed rats 

 and, often, less even than normal non-injected rats. How- 

 ever, such small doses must be given from an early age and 

 have little effect if first injected when growth is nearing com- 

 pletion. The inhibition of growth due to larger doses of 

 oestrone (e.g., 0.02 mg. on alternate days) affects the glands 

 of internal secretion and, with the exception of the hver, al- 

 most all the other viscera including the central nervous sys- 

 tem. Zondek used large doses of oestradiol benzoate in his ex- 

 periments (e.g., 180,000 mouse-units of "Dimenformon" in 

 18 weeks). He concluded that the dwarfing of rats by this 

 treatment was caused by a marked hypophysial deficiency, 

 which in some cases was complete, inasmuch as no further 

 growth occurred after treatment was stopped, unless anterior 

 pituitary growth-promoting extract was injected. Zondek, 

 also, performed experiments with fowls in which he observed 

 osteosclerosis (femur, tibia, and fibula). ^ 



2. The thyroid. — The possible importance of the thyro- 

 tropic hormone as a participant in the growth effects of an- 

 terior pituitary extract has already been discussed. There 

 can be no question concerning the inhibition of growth which 

 may appear if complete thyroid deficiency is produced early 

 in life — a statement again emphasized by the recent study of 



'^ Shumacker and Lament (1935) were unable to detect any change in the growth 

 of 6 rats receiving 9 rat-units of oestrone daily between the ages of 23 and 90 days. 



s Numerous other observations on the effects of oestrogens on the pituitary and 

 its secretions are discussed elsewhere (particularly chaps, i and iii). Lauson, Heller, 

 and Sevringhaus (1937) studied the effects of an oestrogen in the mature spayed 

 rat. They particularly investigated the pituitary, adrenals, and thymus. 



[40I 



