Figure 2.

Localized contractile stimulus redirects the flow of cortical pigment granules toward the site of application. Controls show pigmentation before the addition of PMA (no stimulus) and the preprogrammed cortical flow of pigment granules resulting from global application of PMA (global stimulus). In oocytes subjected to the localized application of PMA to the animal pole region (AP stimulus), the side (side stimulus; applied on the right side of the oocyte), and the vegetal pole region (VP stimulus), cortical flow is revealed by the movement of pigment granules toward the region of stimulus.