ENZYME DISTRIBUTION IN THE RAT FETUS AND PLACENTA FOLLOWING THE ADMINSTRATION OF ETHIONINE

Enzyme changes which accompany ethionine-induced resorption of the rat conceptus have been studied by both histochemical and biochemical techniques. Pregnant rats were injected with ethionine over a 3-day period prior to autopsy on day 12 of pregnancy. Sections of the whole conceptus were studied for acid phosphatase with both the Burstone and Gomori methods and for succinoxidase activity with nitro-BT. Biochemical determinations of cathepsins, acid phosphatase, and succinoxidase were performed on homogenates of the fetuses, placentae, and deciduas basalis from ethionine-treated and saline-treated rats. The histochemical study has shown that resorption is accompanied by an increase in the size and number of acid phosphatase granules in the decidual tissues and a concurrent loss of acid phosphatase granules in the fetal tissues. Biochemical methodology indicated that there was no increase in total cathepsin or acid phosphatase activities in the resorbing tissues. No change in succinoxidase activity was found with either histochemical or biochemical techniques. The significance of these results was discussed with reference to the lysosome hypothesis.