Intracellular Localization of I 131 Tagged Lactogenic Hormone in Mammary Gland of Rabbit

Abstract

Summary

The lactogenic-I₁₃₁-tagged hormone was injected intraductally into the mammary glands of rabbits at the end of pseudopregnancy. After 45 to 95 minutes. the glands were removed and the components of the cells were separated. I t was shown that the radioactive lactogenic hormone was localized, to a great extent, in the particulate iractions of the mammary cells. The nuclei and supernatant portions of the cell contained little hormone. These data suggest that the site of activity of the horrnone is primarily in association with the mitochondria and microsomes of the cells and, therefore, that the particulates of the mammary gland cells play important roles in the synthetic activity oi the cells.