Fertilization of the mouse oocyte: Sequence and timing of nuclear progression to the two-cell stage

摘要: From 88 superovulated, mated CFI (Carworth) females, 2643 eggs were collected at two hourly intervals between 12 and 36 hours after administration of human chorionic gonadotrophin then fixed, stained examined as whole-mounts by light microscopy. Mating ovulation essentially complete 10 14 respectively. Metaphase II oocytes continued to decrease in number until 20 hours. Telophase II, a maximum 16 (22% all oocytes), was not seen Pronuclei first appeared 24 hours, 87% the ova pronuclear. Metaphase cleavage, detected 28 represented 17% 32 The cleavage division occurred 30 34 hours. The pronuclear chromatin network, which is always visible, more diffuse larger, male pronucleus. During prophase, strands shorten distinct chromosomes appear, those origin being less condensed. chromosome groups combine form metaphase. Pronuclear fusion observed. Twenty-three per cent had undergone hours: 6% earlier stages presumably arrested while 14% fragmented or degenerated metaphase chromosomes. Anomalies oocyte maturation fertilization accounted for 1.6% ova.