Abstract
AbstractIn the absence of hormone (1‐methyl adenine, 1‐Ma) oocytes from three different species of starfish have been induced to undergo cytoplasmic maturation, including polar body extrusion, sperm aster differentiation, and pronuclear development by mechanical disruption of the germinal vesicle. The factors responsible for aster and pronuclear differentiation appear to develop independently of protein synthesis as observed following an incubation in cycloheximide. The effect of the drug diamide suggests, however, that phosphorylation of preexisting proteins might be involved in this process. While 1‐Ma applied to fertilized, enucleated oocyte fragments is only able to induce sperm aster differentiation without male pronuclear development, both processes occur under the influence of nucleoplasm, without previous hormone treatment. These results suggest that substances originating in the germinal vesicle induce cytoplasmic maturation, i.e., the development of polar bodies, sperm asters, and pronuclei, and question whether there is a direct role of the maturation promoting factor in these processes.
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