RELATION OF PROLAN TO THE ANTERIOR HYPOPHYSEAL HORMONES

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Abstract
Prolan does not easily repair the gonadal deficiencies of hypophysectomized animals (dog, rat), while hypophyseal hormones do. There is a limiting weight for the ovary which can be attained by giving prolan to the immature rat within a definite time interval (100 hrs.), while with hypophyseal hormones the degree of development corresponds to the dose level. Very small amounts of prolan give the maximal effect on the ovary. Much greater amounts of hypophyseal hormone are required, but higher doses of the latter give heavier ovaries than can be produced by any amount of prolan. Prolan combined with amounts of crude hypophyseal hormone giving minimal effects, produces ovaries equal to those maximally obtainable with hypophyseal hormones. Maximal effects are also produced by adding prolan to the sex-free growth hormone. The activation is specific since destruction of the growth factor destroys the effect. Low concentrations of pure hypophyseal sex hormone combined with prolan do not show activation effects, while the sex-free growth hormone is typically activated.