Cellular mechanisms of protein metabolism in the nephron. VI. The immunological demonstration of egg white in droplets and other cellular fractions of the rat kidney after intraperitoneal injection.

Immunological analysis with a specific antiserum showed an increasing concentration of egg white proteins in the cortex of the kidney of the rat up to 18 hours after their intraperitoneal injection, and a fall in the following 40 hours. Homogenates of the cortical tissue prepared at 18 hours, the period of maximum droplet development, showed a large amount of the egg white proteins in the supernatant, considerable amounts in the fraction which contained the mitochondria, but the highest concentration, 6 times that of any other cell fraction, in the highly purified preparation of droplets. The relation of these findings to the morphological and histochemical evidence concerning the constitution of the droplets is discussed and the conclusion drawn that absorbed egg white proteins and mitochondrial substances are important elements in their formation.