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Headfold-stage rat embryos, when cultured on cow serum without supplemental methionine, failed to close their neural tubes, lacked eyes and branchial arches, were abnormally shaped and were reduced in protein content compared to methionine-supplemented embryos. Methionine was essential during the first 18 h of culture, a period in which neural tube closure(More)
Effects of heat shock on the development of early pre-somite embryos have been studied using cultured rat embryos. The results illustrate the sensitivity of the developing head and brain to elevated temperatures prior to neural tube closure and the capacity of embryos to acquire thermotolerance. Embryos exposed briefly to an elevated temperature (43 degrees(More)
Isolated yolk-sacs of chick embryos secreted serum proteins when incubated in buffered chick Ringer's solution. The presence of serum transferrin, two embryo-specific alpha-globulins, and a prealbumin were demonstrated by acrylamide gel analysis. Yolk-sacs from embryos explanted at 11-13 somites (40 hr preincubation) and cultured for 48 hr secreted in(More)
Head fold stage rat embryos were cultured for 48 hours in vitro on serum taken at various intervals from rats that had been injected ip with either cadmium or cyclophosphamide. Their response was compared to that of embryos cultured for the same period on control serum to which these substances were added directly. One and 4 hour sera from cadmium-injected(More)
Research has previously shown that, without methionine supplements, neural tube proteins of rat embryos cultured on bovine sera were hypomethylated and neural tubes failed to close. In the present study, to identify the proteins that became methylated during neurulation, rat embryos were first cultured on methionine-deficient bovine serum for 40 hr, then(More)
Whole rat embryos of 9.5 gestational days were cultured for 2 d on sera taken from rats fed diets deficient in zinc (0.5 micrograms Zn/g diet) or copper (0.6 micrograms Cu/g diet), or fed a control diet (100 micrograms Zn and 10 micrograms Cu per g diet). Head malformations were observed in embryos cultured on 12 of 16 zinc-deficient and 11 of 12(More)
Growth of head-fold-stage rat embryos cultured with human serum for 48 hours was enhanced by supplementation with glucose. Embryo growth (protein and DNA contents) varied with the source of the serum. Serum from 16 of 19 untreated subjects produced normal embryos. Serum from five subjects undergoing cancer chemotherapy and six subjects receiving(More)
Endodermal cells isolated from the yolk sacs of day 3 chick embryos were able to activate metabolically cyclophosphamide. This was demonstrated by the cytotoxicity of cyclophosphamide to the endodermal cells themselves as well as by the ability of endodermal tissue to mediate a cytotoxic response in coculture with KB cells, a human tumor cell line unable to(More)