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.