Sea urchin eggs were injected with rh phalloidin then fertilized. The sequence shows staining at 1 min, 3:40, 5:50, 8:40, 12:25, 14:15, 18:00, 21:00, and 23:15 after fertilization. The staining corresponds well with the rh phalloidin staining of the fertilization cone in fixed eggs. The large dark circle is the egg nucleus. The smaller dark circle barely visible in the next to last image is the sperm nucleus.

This sequence as a movie (1.2 MB).

Rh phalloidin injected eggs go on to divide normally, showing that these doses are not toxic. However, rh phalloidin may cause stabilization of actin filaments, so it is not clear to what degree these images represent what normally happens with respect to actin at fertilization.


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