Nuclear cytochemical changes in rat adrenal glands stimulated by adrenocorticotrophic hormone

Mouse embryos were grown in vitro from the 2-cell or 8-cell to the blastocyst stage in the presence of DNA. Blastocyst diameter and cell number were increased when freshly prepared DNA was used, but stored material was deleterious. Comparisons of the uptake of tritiated DNA in high molecular weight form with that of DNA degraded by shearing or sonication, and with the uptake of tritiated thymidine, showed that less radioactivity was incorporated when the molecular weight of the DNA was reduced. The data suggest that polymerized DNA can be taken into the embryo, but no evidence of integration was obtained. Treatment of embryos homozygous for several recessive alleles with DNA from a strain carrying the corresponding dominants failed to induce any detectable modifications in either the treated animals or their progeny.