Visualization of secretory activities in the Xenopus neurohypophysis by a high S/N video camera

The optical turbidity of neurohypophyses of the frog Xenopus laevis was observed with the help of a high signal to noise ratio video camera and a high speed image processor. Electrical stimulation of the pituitary stalk induced a decrease in turbidity of the neurohypophysis. This response was visualized on a monitor screen as a diffuse pattern consisting of many bright spots. The diameters of these spots were similar to those of individual nerve terminals, indicating that the optical response arises from a structural change in individual nerve terminals upon secretory activation.