Fig. 5. Inhibition of Pn formation leads to persistent Ca²⁺ oscillations after inactivation of Cdk1-cyclin B and MAP kinase. Microinjection of WGA inhibits Pn formation in mouse oocytes (A). Hoechst (i and ii) and Bright field images (iii and iv) of WGA-injected (i and iii) and uninjected (ii and iv) eggs are shown 6 hours after fertilization. Note the lack of any discernable pronuclei in WGA-injected eggs. Cdkl-cyclin B (Bi) and MAP kinase (Bii) activity declines at fertilization with similar kinetics in WGA-injected (grey columns) and control eggs (black columns). Data are from two experiments, each with two replicates. Fertilization of WGA-injected eggs leads to persistent Ca²⁺ oscillations (n=16) (Ci) that last significantly longer than controls (n=13) (Cii,D). Data show the mean±s.d.