The video sequence at the right demonstrates the movements of
Nile blue spots applied to the subcortical layer of a Xenopus
oocyte following fertilization. During the ensuing subcortical rotation
movements, the dense, yolky vegetal deep cytoplasm rotates with
respect to the overlying cortex
to produce a 30 degree relative rotation. This classic footage
provided by Dr. J.-P. Vincent was acquired using a fluorescence
microscope and a sensitive video camera.