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C. L. Chatot, C. A. Ziomek, B. D. Bavister, J. L. Lewis and I. Torres

Summary. One-cell CF-1 × B6SJLF1/J embryos, which usually exhibit a 2-cell block to development in vitro, have been cultured to the blastocyst stage using CZB medium and a glucose washing procedure. CZB medium is a further modification of modified BMOC-2 containing an increased lactate/pyruvate ratio of 116, 1 mm-glutamine and 0·1 mm-EDTA but lacking glucose. Continuous culture of one-cell embryos in CZB medium allowed 83% of embryos to develop beyond the 2-cell stage of which 63% were morulae at 72 h of culture, but blastocysts did not develop. However, washing embryos into CZB medium containing glucose after 48 h of culture (3-4-cell stage) was sufficient to allow development to proceed, with 48% of embryos reaching the blastocyst stage by 96 h of culture. Exposure of embryos to glucose was only necessary from the 3–4-cell stage through the early morula stage since washing back into medium CZB without glucose at 72 h of culture still promoted the development of 50% of embryos to the blastocyst stage. The presence of glucose in this medium for the first 48 h of culture (1-cell to 4-cell stage) was detrimental to embryo development. Glutamine, however, exerted a beneficial effect on embryo development from the 1-cell to the 4-cell stage although its presence was not required for development to proceed during the final 48 h of culture. Blastocysts which developed under optimum conditions contained an average of 33·7 total cells. The in-vitro development of 1-cell embryos beyond the 2-cell stage in response to the removal of glucose and the addition of glutamine to the culture medium suggests that glucose may block some essential metabolic process, and that glutamine may be a preferred energy substrate during early development for these mouse embryos.

Keywords: mouse; embryo; 2-cell block; glutamine; glucose

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C. A. Nagle, N. Paul, I. Mazzoni, S. Quiroga, M. Torres, A. F. Mendizabal and Z. Farinati

Summary. In basal conditions, progesterone concentrations were similar in the ovarian veins of the ovary +CL (3211 ± 526 ng/ml) and the ovary −CL (3165 ± 554 ng/ml), but after blocking the blood flow between the ovary +CL and the uterus, the progesterone values in the vein draining the ovary −CL decreased to 1218 ± 394 ng/ml (P < 0·01), When [3H]progesterone was injected in the ovary +CL, the radioactivity appeared earlier and more concentrated in the vein draining the ovary −CL (30 sec, 0·53% of injected dose) than in the femoral vein (150 sec, 0·08% of injected dose). Removal of the ovary +CL was followed by a brief maintenance of peripheral progesterone within luteal-phase levels. The in-vitro progesterone production by a suspension of cells isolated from the corpus luteum was 47·5 ± 12·8 ng/ml/2 h, whereas luteal-like cells isolated from the ovary −CL secreted 14·3 ± 6·0 ng/ml/2 h (P < 0·01) into the medium. We therefore suggest that the symmetrical and high secretion rate of progesterone by the ovaries of the capuchin monkey indicates a between-ovary communication system, and that the luteal-like tissue of the ovary −CL can produce relatively large amounts of progesterone.

Keywords: capuchin monkey; luteal phase; ovarian vein; progesterone