Practice question

During fertilization, maternal and paternal pronuclei must migrate centrally and meet before first mitosis for syngamy and diploidy. Sperm aster nucleated by centriole centrosome extends astral microtubules interacting with cortex. Dynein heavy chain DHC-1 with dynactin DNC-1, adaptor LIS-1, and nuclear envelope bridge SUN-1/ZYG-12 KASH drives minus-end directed pulling forces anchored at cortex. Cytoplasmic dynein reels pronuclei inward while pushing female pronucleus posteriorly. Kinesin KLP-18 opposes but dynein dominates net movement. Dynein inhibition via RNAi causes pronuclei to remain peripheral and asymmetric division failure.