Abstract
Summary
Thirty oöphorectornized, virgin rabbits, injected subcutaneously 5 days weekly for 4 weeks with 200 I.U. of estrone and 1 I.U. of progesterone showed prolactational mammary growth approximating that of a 3-weeks′ pregnant rabbit. Three days after the last of these injections, 5 different levels of lactogenic hormone were tested on groups of 6 rabbits. The hormone was given intraductally in such a way that an individual sector in each animal received a constant volume of fluid (1.0 cc). Of the different doses of hormone tested, 6 and 3 I.U. caused localized sector lactation in all 6 animals; 1.5 I.U. in 5 of 6; and 0.75 I.U. in 3 of 6 animals. None of the 6 animals injected with 0.37 I.U. lactated; nor did the uninjected or control-injected sectors in any animal lactate. This experiment demonstrates for the first time that the hypophysial lactogenic hormone has a direct mammotrophic effect just as it was previously shown to have a direct crop sac stimulating action. With all other factors essentially equal in any 2 adjoining sectors in a mammary gland, the mere bathing of the parenchyma of one with 25 μg of this purified protein brought about the complex cell-growth and cell-renewal processes of lactation, whereas the introduction of a control solution or no treatment whatsoever, caused no detectable change in the other.
The estroiie and progcutcronc used in this study wcre generously supplied by Parke, Davis and Company, Detroit, Mich.
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