ABSTRACT
In non-fertilized egg cortex a continuous meshwork composed of fibrils and trabecules of various diameter and short microfilaments attached to the cortical granules and to small electrondense condensations was demonstrated. The cortical cytoskeleton of fertilized eggs consists of numerous microfilaments, single or in bundles. Cortex rigidity was found to correlate with the frequency of experimental polyembryonia occurrence. The largest amount of twins forms after centrifugation for the first 1–6 min of zygote development. The tv/ins may be obtained at 25–40 min of development by centrifugation in the presence of cytochalasin B. Morphogenetic role of cortex in development of sea urchins twins has been discussed.
