[Exogenous peroxidase in the eggs of rats during cleavage]

The presence of exogenous peroxidase of the rat's eggs during cleavage at the 1-, 2-, 8-cellular stages and the blastocysts were studied after 30 minute incubation with horseradish peroxidase (molecular weight 40.000, approximate size of the molecule 40 A). The activity of exogenous peroxidase in the area of zona pellucida was established in the perivitelline space, in the cytoplasm - in the pinocytosis vesicles, in certain greater vacuoles and in certain secondary lysosomes. At the stage of blastocyst the penetration of exogenous protein was greater than at earlier stages. The reaction product was found here in the intercellular space and in the blastocyst cavity. The obtained data suggest possible penetration of the protein from the surrounding area into the egg during its passing the uterine tube. The substances influencing the differentiation of the egg or teratogens may penetrate the egg in the same way.