Figure 8.

Oocytes are less sensitive to IP₃ than mature eggs. Stage VI oocytes were coinjected with 20 μM Ca²⁺ green dextran and the indicated concentration of caged IP₃. Some of these oocytes were matured in progesterone. During the 15-s period indicated by the arrowhead, the immature oocyte or mature egg (3 h after GVBD) was exposed to UV light to activate the caged IP₃. Traces show Ca²⁺ green fluorescence as a function of time for caged IP₃ at 0.1, 1.0, and 10 μM. The dotted line represents an extension of the baseline. Quantitation of these experiments is shown in Table 1.