STUDIES ON THE TRANSFER OF PROTEIN ACROSS THE GLANDULAR EPITHELIUM OF THE MAMMARY GLAND DURING INVOLUTION

Summary In the present paper then movement of protein across the glandular epithelium of the mammary gland during involution has been studied. The movement of protein from the gland was followed by infusing [131I]‐labelled protiens into the mammary gland and measuring either the concentration of labelled protein remaining in the gland or the amount of labelled protein appearing in the efferent mammary lymph. The protein composition of the secretion in the mammary gland at different stages of involution was studied by immunoelectrophoresis and by separating the secretion on Sephadex G‐200 or DEAE Sephadex. The results of the absorption experiments have been discussed in relation to the changes observed in the concentration of the serum proteins in the secretion during involution.