Fusion of bull and human sperm with Nicotiana protoplasts

Bull and human spermatozoa were fused with Nicotiana tabacum leaf protoplasts by using polyethylene glycol (PEG). After fusion the cell components were cultured for 20 and 48 hours. Electron microscopy and Nomarski optics were used to control the process. After fusion between bull sperm and protoplasts the following was observed. (1) One or several spermatozoa penetrated into single protoplasts. (2) In electron microscope sections the sperm heads can be seen to be in contact with the plant organelles. (3) Nuclear fusion resulted in one or several sperm nuclei fusing with the nuclei of Nicotiana and the chromatin of the sperm decondensing. (4) The fusion also occurs without PEG under spontaneous conditions. The human sperm also penetrates into the protoplasts and can be seen in E.M. sections in contact with the chloroplasts. The fusion also occurs under spontaneous conditions when living human spermatozoa are mixed with protoplasts. There are several similarities between this type of fusion and fertilization occurring in animals. The implications of the experiments are discussed.