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A cell-free preparation of the cytoplasm from activated eggs of Rana pipiens induces, in demembranated sperm nuclei of Xenopus laevis, formation of a nuclear envelope, chromatin decondensation, initiation of DNA synthesis, and chromosome condensation. Both soluble and particulate cytoplasmic constituents are required to initiate these processes in vitro.(More)
A cell-free cytoplasmic preparation from activated Rana pipiens eggs could induce in demembranated Xenopus laevis sperm nuclei morphological changes similar to those seen during pronuclear formation in intact eggs. The condensed sperm chromatin underwent an initial rapid, but limited, dispersion. A nuclear envelope formed around the dispersed chromatin and(More)
Much interest in vertebrate embryology is now focused on early pattern formation in the frog, Xenopus laevis. In this species, the body plan is specified by a stable positional system set up by a cytoplasmic rotation in the zygote that occurs before first cleavage. Perturbation of this initial cellular event by a variety of means causes permanent(More)
Although application of the Edmonton protocol has markedly improved outcomes for pancreatic islet transplantation, the insulin independence rate after islet transplantation from one donor pancreas has proven to remain low. During the isolation process and subsequent clinical transplantation, islets are subjected to severe adverse conditions that impair(More)
We investigated the effects of puromycin on mouse oocyte chromosomes during meiotic maturation in vitro. Puromycin treatment for 6 hr at 100 micrograms/ml almost completely, but reversibly, suppressed [35S]methionine incorporation into oocyte protein at all stages of maturation tested. Nevertheless, oocytes treated at the germinal vesicle stage underwent(More)
Zona-free oocytes of the mouse were inseminated at prometaphase I or metaphase I of meiotic maturation in vitro, and the behavior of the sperm nuclei within the oocyte cytoplasm was examined. If the oocytes were penetrated by up to three sperm, maturation continued during subsequent incubation and became arrested at metaphase II. Meanwhile, each sperm(More)