Figure 1.

Actin is reorganized at egg activation. Time series of an ex vivo‐activated mature oocyte (a–c; n = 6) and in vivo‐activated egg (d; n = 4) expressing F‐Tractin.tdTomato. Maximum Z‐projection (a–d), three‐dimensional (3D) projection at a 45° angle (a′–d′) and a single Z‐plane at 20 µm depth (a″–d″) are shown for each time point. Images were acquired using an Olympus FV3000 confocal microscope. (a–a″) Before the addition of activation buffer, actin is in a smooth cortical distribution around ridges in the cortex (as shown in Movie 1). (b–c″) Following egg activation (3–12 min, as shown in Movie 2) and (27–35 min, as shown in Movie 3), actin is reorganized in larger, more widely distributed foci. 3D projection shows that the cortex has expanded and that actin is no longer associated with the ridge. Single plane images show that a cortical enrichment preactivation is lost and that actin is not as enriched at the cortex after activation. (d–d″) In vivo‐activated eggs collected from the oviduct have a similar actin distribution as mature oocytes activated ex vivo (compare c–c″ [Movie 3] to d–d″ [as shown in Movie 4]). Scale bar = 10 µm (a–d′)