Intracellular Localization of I131 Tagged Lactogenic Hormone in Mammary Gland of Rabbit

Abstract

The lactogenic-I131 tagged hormone was injd. intraductally into the mammary glands of rabbits at the end of pseudopregnancy. After 45 to 95 min., the glands were removed and the cell components separated. The radioactive lactogenic hormone was localized, to a great extent, in the particulate fractions 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 hormone is primarily associated with the mitochondria and microsomes and, therefore, that the particulates of the mammary gland cells play important roles in their synthetic activity.