Post-fusion reaction of mouse oocyte cortex to incorporated thymocyte cells

Abstract
Ovulated alcohol-activated or inactivated mouse oocytes were fused with mouse thymocytes. Activated oocytes react to the presence of foreign nuclei by forming in the peripheral cytoplasm incorporation cones. In this region the cell membrane is smooth and cortical layer of thin filaments underlies it. It resembles the fertilization cone. In non-activated oocytes a layer of thin cortical filaments of the same thickness is formed over the foreign chromatin but the surface proturberance (cone) is absent. These result suggest that the cortical alteration in the oocyte architecture may be a general reaction of the oocytes surface to various chromatins introduced, not only to sperm chromatin. The role of oocyte activation in the evolution of these cortical changes is discussed.