Abstract
It has been shown previously that the removal of the thyroid glands induces a very marked hypertrophy of the liver in both male and female ducks, mostly through an increase of the lipids, and that the injection of anterior pituitary extract enhances this hypertrophy. 1
Other experiments were made on 38 ducks (with 33 controls) in order to study the weight of the liver under different experimental conditions:∗ thyroidectomy, injections of different pituitary extracts, of urinary extract, and of benzogynoestryl 2 with varying degrees of illumination. The size of the testes, which depends upon the intensity of the illumination 2 was shown to be related to the size of the liver.
Table I shows that thyroidectomy is followed by a marked increase in the weight of the liver. On the other hand, this operation delays the testicular growth induced by illumination, as has been shown in another paper. 4 When in the thyroidectomized animals the testes have grown to some extent, the increase of the liver is less marked. Such an inverse relation between testes and liver has been observed in the pigeon by Schooley and Riddle. 3
Anterior lobe extract induced in 2 ducks a hypertrophy of the liver. Extract of pregnancy urine (Antuitrin S) gave no significant changes, but prolactin did increase the weight of the liver.‡
The injection of pituitary extract seems to have increased the response of the liver in a thyroidectomized duck. A similar result had already been obtained in 2 thyroidectomized animals. 1
The injection of benzogynoestryl (Roussel) induced an increase of the weight of the liver. Further experiments will show if the female sex hormone secreted by the ovary is responsible for the heavier liver in the female than in the male (Cf. table and 1 ).
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