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114 HomeA scanning electron micrograph of human sperm and oocyte
from the Sea
Urchin Embryology Tutorial
from LIFE: The Science of Biology, Purves
et al, 1998
from LIFE: The Science of Biology, Purves
et al, 1998
Click on the image below to watch a movie showing the events involved in the slow block to polyspermy! This movie shows simultaneous double imaging of phase contrast (left) and intracellular Ca ++ concentration (right) during sea urchin fertilization. The left image shows the approach of the sperm at about 2 o'clock and the rising of the vitelline membrane. Intracellular Ca++ is monitored by an indicator that becomes more fluorescent when it binds Ca++. A transient Ca++ rise around the entire cortex (fifth frame) is followed by the Ca++ wave, which begins at the sperm entry site.
image and movie from Mark Terasaki